The main problem with that work of the flesh which Paul calls "party spirit' (Galatians 5:20) is that it urges people to evaluate Church teaching in light of their sect's pet doctrines instead of evaluating their sect's pet doctrines in light of Catholic teaching.  So, for instance, Calvinists filter Catholic teaching through a few pet doctrines about the sovereignty of God and predestination and original sin, while universalists filter Catholic teaching through a few pet doctrines about the love of God and the hope of heaven. Other pertinent considerations get filtered out.

Party spirit is a major affliction of modern Americans, Catholic and non-Catholic.  And it tends to be expressed in different ways depending on the party's needs.  For instance, party spirit can radically warp a healthy Catholic understanding of conscience.  So, one the one hand, you get discourse from some sectors representing the Don't Form Your Conscience doctrine, when the Party needs you to think that.  What do I mean?  When somebody like Nancy Pelosi stands up and declares that her Catholic faith "compels" her to support gay "marriage" she is making what I call the "something something conscience something something' argument.  Basically what she means is that all you need to do to appeal to "conscience" is to have a really strong feeling.  You don't actually need to educate yourself about what the Catholic Church you are invoking actually teaches about the ontological impossibility of gay "marriage".  You simply have to say, "The Church says to follow your conscience, not form or educate it.  My really strong feeling is that gay 'marriage' is fine.  So it is."

Of course, Pelosi doesn't beleve other people should be allowed to follow their conscience when it comes to gay "marriage".  So she brutally denounces as "frauds" those chaplains who have real issues of conscience about gay "marriage".

This means that, in addition to the Don't Form Your Conscience doctrine, there is also the Don't Follow Your Conscience doctrine when the Party requires that.  What both doctrines have in common is "Party needs trump Church teaching".  And it's a black thread that binds both political parties together in a secret bond and makes partisans of both parties brothers under the skin.

And so, in addition to Pelosi simultaneously appealing to her ignorant "conscience" in order to prop up Dem dogma about gay "marriage" while shouting down other people's informed conscience in order to prop up Dem dogma about gay "marriage", you can also find things like this on the Right:

Now with somebody like Nancy Pelosi, who has never evidenced the slightest understanding of her Catholic faith as anything other than a tool for acquiring power, and whose public pronouncements on it have been of such immovable and unteachable stupidity as to persuade me she knows nor cares not one thing about the Catholic faith beyond its political utility, I just don't expect much.

But when Catholics who purport to know the faith talk to me, I expect much more since those to whom much is given, much will be required, as our Lord said.  So I think it particularly dangerous when, under the influence of party spirit, conservative Catholics start arguing that the solution to the Pelosiesque hogwash of "something something conscience something something" is, as above, "Do not vote your conscience".

Sorry, but rejecting one's conscience altogether is just as poisonous--indeed more poisonous--than refusing to form it.  And under the influence of party spirit, Catholics can often be inveigled into buying these two options --Don't Form Your Conscience/Reject Your Conscience--as the only possibilities there are.

Understand: my point here is not about who you will choose to vote for.  My point is that the way this particular graphic (and a lot of arguments like it) works is to say, "Obeying your conscience is contemptible."  This one happens to be an attempt to denounce conscience on behalf of Romney, but I could just as easily find arguments from previous elections in which lefties made exactly the same attempt to denounce the consciences of Nader supporters.  The problem is not that somebody is trying to persuade somebody of the merits of their major party candidate.  It's that in attempting to do so, arguments like the one in this graphic specifically argue that those who obey their consciences to the best of their ability should stop doing that and instead violate their conscience in order to serve party spirit.

Attempting to shout down and smash conscience is what Catholic teaching calls "evil".  It's evil when Pelosi does it to try to smash Catholic consciences about gay "marriage" or contraceptives or abortion and it's just as evil when some zealous righty tries to smash a Catholic's conscience and force them to get on board with party spirit for the Home Team.

What the Church actually teaches is this: a person must--absolutely must, without any exceptions whatsoever--always obey the certain judgment of his or her conscience (CCC 1800).  Anybody from any party that tells you otherwise is a false prophet and an agent of hell.  That said, what conscience must also always do is be formed more and more closely in the image of Christ so that we do not erroneously obey a false or badly formed conscience. So a mere "strong feeling" that directly contradicts the immemorial teaching of the Church is not the "certain judgment of conscience" but the ignorant guess (and, in the case of somebody who refuses the Church's guidance, the arrogant rejection) of light and life. Since this is, surprisingly, news for an awful lot of people, permit me to reproduce here the Church's full teaching on conscience from the Catechism.  It is plain, simple, lucid common sense.  But as the examples above from everyday American moral discourse make clear, it appears to be one of the Church's best-kept secrets:

1776 "Deep within his conscience man discovers a law which he has not laid upon himself but which he must obey. Its voice, ever calling him to love and to do what is good and to avoid evil, sounds in his heart at the right moment. . . . For man has in his heart a law inscribed by God. . . . His conscience is man's most secret core and his sanctuary. There he is alone with God whose voice echoes in his depths."47

I. THE JUDGMENT OF CONSCIENCE

1777 Moral conscience,48 present at the heart of the person, enjoins him at the appropriate moment to do good and to avoid evil. It also judges particular choices, approving those that are good and denouncing those that are evil.49 It bears witness to the authority of truth in reference to the supreme Good to which the human person is drawn, and it welcomes the commandments. When he listens to his conscience, the prudent man can hear God speaking.

1778 Conscience is a judgment of reason whereby the human person recognizes the moral quality of a concrete act that he is going to perform, is in the process of performing, or has already completed. In all he says and does, man is obliged to follow faithfully what he knows to be just and right. It is by the judgment of his conscience that man perceives and recognizes the prescriptions of the divine law:

Conscience is a law of the mind; yet [Christians] would not grant that it is nothing more; I mean that it was not a dictate, nor conveyed the notion of responsibility, of duty, of a threat and a promise. . . . [Conscience] is a messenger of him, who, both in nature and in grace, speaks to us behind a veil, and teaches and rules us by his representatives. Conscience is the aboriginal Vicar of Christ.50
1779 It is important for every person to be sufficiently present to himself in order to hear and follow the voice of his conscience. This requirement of interiority is all the more necessary as life often distracts us from any reflection, self-examination or introspection:

Return to your conscience, question it. . . . Turn inward, brethren, and in everything you do, see God as your witness.51
1780 The dignity of the human person implies and requires uprightness of moral conscience. Conscience includes the perception of the principles of morality (synderesis); their application in the given circumstances by practical discernment of reasons and goods; and finally judgment about concrete acts yet to be performed or already performed. The truth about the moral good, stated in the law of reason, is recognized practically and concretely by the prudent judgment of conscience. We call that man prudent who chooses in conformity with this judgment.

1781 Conscience enables one to assume responsibility for the acts performed. If man commits evil, the just judgment of conscience can remain within him as the witness to the universal truth of the good, at the same time as the evil of his particular choice. The verdict of the judgment of conscience remains a pledge of hope and mercy. In attesting to the fault committed, it calls to mind the forgiveness that must be asked, the good that must still be practiced, and the virtue that must be constantly cultivated with the grace of God:

We shall . . . reassure our hearts before him whenever our hearts condemn us; for God is greater than our hearts, and he knows everything.52
1782 Man has the right to act in conscience and in freedom so as personally to make moral decisions. "He must not be forced to act contrary to his conscience. Nor must he be prevented from acting according to his conscience, especially in religious matters."53

II. THE FORMATION OF CONSCIENCE

1783 Conscience must be informed and moral judgment enlightened. A well-formed conscience is upright and truthful. It formulates its judgments according to reason, in conformity with the true good willed by the wisdom of the Creator. The education of conscience is indispensable for human beings who are subjected to negative influences and tempted by sin to prefer their own judgment and to reject authoritative teachings.

1784 The education of the conscience is a lifelong task. From the earliest years, it awakens the child to the knowledge and practice of the interior law recognized by conscience. Prudent education teaches virtue; it prevents or cures fear, selfishness and pride, resentment arising from guilt, and feelings of complacency, born of human weakness and faults. The education of the conscience guarantees freedom and engenders peace of heart.

1785 In the formation of conscience the Word of God is the light for our path,54 we must assimilate it in faith and prayer and put it into practice. We must also examine our conscience before the Lord's Cross. We are assisted by the gifts of the Holy Spirit, aided by the witness or advice of others and guided by the authoritative teaching of the Church.55

III. TO CHOOSE IN ACCORD WITH CONSCIENCE

1786 Faced with a moral choice, conscience can make either a right judgment in accordance with reason and the divine law or, on the contrary, an erroneous judgment that departs from them.

1787 Man is sometimes confronted by situations that make moral judgments less assured and decision difficult. But he must always seriously seek what is right and good and discern the will of God expressed in divine law.

1788 To this purpose, man strives to interpret the data of experience and the signs of the times assisted by the virtue of prudence, by the advice of competent people, and by the help of the Holy Spirit and his gifts.

1789 Some rules apply in every case:

- One may never do evil so that good may result from it;

- the Golden Rule: "Whatever you wish that men would do to you, do so to them."56

- charity always proceeds by way of respect for one's neighbor and his conscience: "Thus sinning against your brethren and wounding their conscience . . . you sin against Christ."57 Therefore "it is right not to . . . do anything that makes your brother stumble."58

IV. ERRONEOUS JUDGMENT

1790 A human being must always obey the certain judgment of his conscience. If he were deliberately to act against it, he would condemn himself. Yet it can happen that moral conscience remains in ignorance and makes erroneous judgments about acts to be performed or already committed.

1791 This ignorance can often be imputed to personal responsibility. This is the case when a man "takes little trouble to find out what is true and good, or when conscience is by degrees almost blinded through the habit of committing sin."59 In such cases, the person is culpable for the evil he commits.

1792 Ignorance of Christ and his Gospel, bad example given by others, enslavement to one's passions, assertion of a mistaken notion of autonomy of conscience, rejection of the Church's authority and her teaching, lack of conversion and of charity: these can be at the source of errors of judgment in moral conduct.

1793 If - on the contrary - the ignorance is invincible, or the moral subject is not responsible for his erroneous judgment, the evil committed by the person cannot be imputed to him. It remains no less an evil, a privation, a disorder. One must therefore work to correct the errors of moral conscience.

1794 A good and pure conscience is enlightened by true faith, for charity proceeds at the same time "from a pure heart and a good conscience and sincere faith."60

The more a correct conscience prevails, the more do persons and groups turn aside from blind choice and try to be guided by objective standards of moral conduct.61
IN BRIEF

1795 "Conscience is man's most secret core, and his sanctuary. There he is alone with God whose voice echoes in his depths" (GS 16).

1796 Conscience is a judgment of reason by which the human person recognizes the moral quality of a concrete act.

1797 For the man who has committed evil, the verdict of his conscience remains a pledge of conversion and of hope.

1798 A well-formed conscience is upright and truthful. It formulates its judgments according to reason, in conformity with the true good willed by the wisdom of the Creator. Everyone must avail himself of the means to form his conscience.

1799 Faced with a moral choice, conscience can make either a right judgment in accordance with reason and the divine law or, on the contrary, an erroneous judgment that departs from them.

1800 A human being must always obey the certain judgment of his conscience.

1801 Conscience can remain in ignorance or make erroneous judgments. Such ignorance and errors are not always free of guilt.

1802 The Word of God is a light for our path. We must assimilate it in faith and prayer and put it into practice. This is how moral conscience is formed.