Up until this point in his epistle, Paul was trying to reestablish his credibility with the Galatians which had been damaged by the agitators from Jerusalem. They claimed Paul owed his knowledge of the Gospel to the Apostles and had no authority to preach anything except what they were teaching at Jerusalem. Nevertheless, Paul began by logically showing the Galatians that he couldn’t owe anything to the Apostles, since he had been evangelizing areas around Damascus for three years before he had even met Peter. Furthermore, he spent so little time in Jerusalem during his first visit there that he couldn’t have obtained much from them in the way of training for evangelism.
After being run out of Jerusalem by loyalists to the high priest for preaching his Gospel there, the disciples took him by night to Caesarea where he sailed to his hometown of Tarsus in Cilicia. He continued to evangelize Cilicia and Syria while folks at Jerusalem simply praised God for what he was doing. When he finally did come to Jerusalem 11 years after his first visit, the leaders there had nothing to add to what he had been preaching. Not only so, but he ended up correcting Peter for not standing his ground in Christ when the men from James came to Antioch. This very confrontation precipitated the Jerusalem Council.
In Chapter 3 Paul began his five theological arguments showing the Galatians that salvation comes by faith alone and not through Law. We find the first of these arguments in Galatians 3:1-5. When the Gospel was first preached to them the Galatians witnessed a vivid portrayal of Jesus crucified before them (Galatians 3:1). That is, not necessarily a detailed description of a crucifixion, but a detailed analysis of the meaning of what the crucifixion accomplished. In the same verse Paul likened the agitators’ message to a sleight of hand version of the gospel, bewitching the Galatians into believing they could believe in Jesus as the Messiah and earn their salvation at the same time. Nothing was up-front about their approach; it was all done through deception.
Paul’s method of convincing the Galatians of the Gospel was completely different. He was completely forthright and even told them about his previous manner of persecuting the Church (Galatians 1:13-14). The Judaizers had ulterior motives for what they did and left a lot of things out in their approach to the Gospel. The result was that the Galatians had separated themselves from the Body of Christ by rejecting faith in favor of works to obtain salvation (Galatians 3:1; cp. 1:6-9). This shouldn’t occur for anyone with spiritual understanding of what Jesus had done for us. Paul likened the Galatians to those who don’t have God’s Spirit.
Paul had one thing in mind: to know of the Galatians whether they received the Spirit of God through works of the Law or through faith in Christ (Galatians 3:2). This inquiry alone should settle the controversy. It is abundantly obvious that they hadn’t received the Spirit through obedience to the Law, but by hearing and believing the Gospel. If someone works for something, it is referred to as wages; it is what is owed to them for their labor. On the other hand, if someone trusts (has faith) for something and receives it, it is called a gift. One is completely dependent upon the trustworthiness of the giver—in this case God—for the gift of his Spirit. Having the Spirit of God is the only evidence that one is a Christian (Romans 8:9).
The question, then, is how did the Galatians acquire the Spirit of God? Did God owe his presence to them? Does he owe his presence to anyone? Paul’s first argument concerns the obvious—God’s presence is a gift! God owes us nothing. What he gives us is given completely through grace. The truth is clear in that one simply cannot cause God to be indebted to us. We are completely at his mercy. Paul is saying that believing is superior to obedience to the Law. Having the Spirit of God is God’s guarantee to our salvation (Ephesians 1:13-14). Therefore, if God’s Spirit comes to us by faith, then our salvation comes by faith alone, not through obedience to the Law.