His letter to the Galatians is one of the most personal of Paul's letters. In it he tells us about his own spiritual journey and about his argument with Peter at Antioch. The passage we read today can seem like a simple piece of rabbinic argument about the interpretation of the law but in it we get another glimpse of Paul's most personal struggle.
He quotes Deuteronomy 21:23, 'cursed be everyone who hangs on a tree'. This text helps to explain Saul's fury, and his conviction of righteousness, in persecuting and even killing Christians. In terms of what the Scriptures taught, what the Christians were proposing was blasphemous and obscene. They were claiming that the Lord, the God of Israel, had shown his power, and revealed his holiness, in an accursed thing, a hanged man.
Saul was moved to imitate Phinehas, praised in the psalms for his defence of God's righteousness (Psalm 106:28-31). A plague afflicted the people as a result of their worship of the Baal of Peor, into which they had been seduced by intermarrying with the Midianites. Phinehas killed a Hebrew man married to a Midianite woman (Numbers 25:1-9): this is the event hidden under the psalmist's innocuous 'Phinehas stood up and intervened'. Phinehas was celebrated as a defender of the holiness of the God of Israel and Saul's zeal was of the same quality: uncompromising, passionate, violent.
The cross of Christ, Paul tells us later, is folly for Gentiles and a stumbling block for Jews: this was Paul's personal difficulty also, an apparently insoluble one, an obstacle that he could not get over. He could not square this circle, that the Lord would reveal his power and holiness in a way that he had earlier declared to be accursed. It was only his encounter with the Risen Lord on the road to Damascus that convinced him of the truth of what the Christians were teaching: Christ has ransomed us from the curse of the law by becoming a curse for us. So the possibility of faith by which human beings share in the righteousness of God, the blessing of Abraham, is extended to the Gentiles through Jesus the Christ.
It was indeed true that God had shown his power and revealed his holiness not in the violence of his would-be defenders but in the death of His Son on the Cross. The obstacle that Paul could not get over then became the key to his whole understanding of God and of God's grace. Towards the end of Galatians he writes 'far be it from me to glory except in the cross of our Lord Jesus Christ' (6:14). And in writing to the Corinthians he returns to the obstacle that becomes the key, 'I decided to know nothing among you except Jesus Christ and him crucified' (1 Cor 2:2).