Why have we been talking for three weeks about the relationship of the Mosaic Law and the Gospel?

Well, in addition to the fact that it’s good to know what the Church teaches about our relationship with our Jewish older brothers, it’s also important if we want to have the foggiest clue of what large portions of the New Testament are about.

For starters, everything from Matthew to John to Romans to Galatians to Hebrews was written under the lash of the urgent pastoral necessity to get the relationship between the Old and New Covenants right.

“Yes,” reply many Catholics, “and that’s just why Bible study is so dry and dull: because the authors of Scripture seem to be concerned about things that are remote from anything that concerns my life in the modern world.”

Here’s the deal: New Testament teaching on this matter is, in fact, not remote from “real life.” To understand why, consider the words of G.K. Chesterton:

“It was no flock of sheep the Christian shepherd was leading, but a herd of bulls and tigers, of terrible ideals and devouring doctrines, each one of them strong enough to turn to a false religion and lay waste the world. Remember that the Church went in specifically for dangerous ideas; she was a lion tamer.

“The idea of birth through a Holy Spirit, of the death of a divine being, of the forgiveness of sins, or the fulfillment of prophecies, are ideas which, anyone can see, need but a touch to turn them into something blasphemous or ferocious. The smallest link was let drop by the artificers of the Mediterranean, and the lion of ancestral pessimism burst his chain in the forgotten forests of the north.

“Of these theological equalizations I have to speak afterwards. Here it is enough to notice that if some small mistake were made in doctrine, huge blunders might be made in human happiness. A sentence phrased wrong about the nature of symbolism would have broken all the best statues in Europe. A slip in the definitions might stop all the dances; might wither all the Christmas trees or break all the Easter eggs.

“Doctrines had to be defined within strict limits, even in order that man might enjoy general human liberties. The Church had to be careful, if only that the world might be careless.”

Likewise, to get wrong the relationship between the Old and New Covenants means everything from banishing the Old Testament from the Bible to embracing freakish licentiousness as “Christian liberty” to pursuing the futile project of trying to earn the love of God to binding the Church with the pitiless rule, “That which is not forbidden is compulsory.” Instead of these or a dozen other confusions, the Church, led by the Spirit, held fast to the common sense of being both one and catholic, of calling us to live the Law by the Spirit, not abolish it.

That is what animates Paul’s thinking. Contrary to many Reactionary Dissenters, the Apostle to the Gentiles did not tell Jewish Christians they could not practice the customs of Moses.

Indeed, Paul himself had one of his Gentile co-workers circumcised so as not to give scandal to Jews he hoped to evangelize (Acts 16:3). Yet he paradoxically insisted that Jewish Christians could not impose their customs on Gentile believers with any claim that they were salvific.

His rule of thumb was that he and his co-workers must be willing to bear any burden for the sake of those with a weak conscience, but he adamantly defied anyone who tried to make human works of the Law a condition of God’s justifying love.

This humane balance is why he could thunder against the circumcision party in Galatians (who sought to earn their salvation instead of receiving it by grace) and yet could write gently to the mixed community at Rome (where some Jewish Christians had scruples about Jewish holidays and diet and Gentile believers did not):

“One man esteems one day as better than another, while another man esteems all days alike. Let everyone be fully convinced in his own mind: He, who observes the day, observes it in honor of the Lord. He also who eats, eats in honor of the Lord, since he gives thanks to God; while he who abstains, abstains in honor of the Lord and gives thanks to God” (Romans 14:5-6).

That wisdom, encoded into the Church’s DNA since the first century, is why the Catholic communion can play host to a huge array of indigenous expressions of faith in Christ to this very day.

From this early controversy springs the sane and human rule, “In essential things, unity; in doubtful things, liberty; in all things, charity.”

Mark Shea is senior content editor for http://www.CatholicExchange.com.