But I, brethren, if I still preach circumcision, why am I still persecuted? Then the stumbling block of the cross has been abolished.Galatians 5:11(NASB)
The main issue that Paul had to deal with in Galatians was legalism, where Jewish believers were reverting to Judaism and insisting Gentiles were circumcised. They believed keeping the Law was necessary for salvation, not realising that the rites, rituals, feasts and sacrifices pointed to Christ.
The Law was designed to identify their sin and their need for a Saviour. It was given by God to point them to Jesus - the Saviour, Whose sinless life fulfilled the Law on behalf of all who would believe. Many Jews were prepared to add "believing in Christ" to their religious rites, but very few could accept the gospel Paul taught - that faith alone in Christ alone was sufficient for salvation and that no man living would be justified by works of the Law. Indeed, Paul suffered much criticism and persecution from these legalists for holding fast to the pure gospel of grace.
One of the covenant signs given to Israel was circumcision. God instructed Abraham to circumcise himself and his household as an everlasting covenant in their flesh. This was the covenant sign between God and Israel but like other works of the Law it had no power to save. Circumcision was to be a physical reminder to Israel of the important spiritual circumcision of the heart, which God desired of His people.
Circumcision of the flesh illustrated a spiritual cutting away of sin from the life of a believer - a spiritual circumcision, which spoke of a life dedicated to God. These legalists, however, berated Paul, insisting that circumcision was also necessary for salvation, which is diametrically opposite of the gospel of grace, for we are not justified by any works of the Law (eg circumcision) but by faith in Christ.
When legalism is adopted as a requirement for righteousness, the glorious gospel of Christ, Who is our righteousness, is abandoned. When circumcision is insisted upon as necessary for salvation, the gospel of grace is nullified, for works of the Law have been added to Christ's finished work of Grace on the cross.
These legalists knew Paul's teaching conflicted with their own doctrine but in Paul's absence, it appears they secured the trust of the Galatian believers and persuaded them to change their belief and add certain aspects of the Law to the requirement for salvation, including circumcision. It seems they claimed Paul changed his position on circumcision and was now promoting it, alongside faith in Christ!!! Nothing could be further from the truth and Paul vigorously defended the freedom we have in Christ and outlined the dangers of legalism.
He insisted that the gospel of grace has freed us from the curse of the Law, which he labelled a "yoke of slavery". Paul rejected this teaching and insisted that faith in Christ is the one and only way to be justified before God, and in chapter 1, he even pronounced a curse on anyone who taught a different gospel: "if we, or an angel from heaven, should preach to you a gospel contrary to what we have preached to you, he is to be accursed! - and I say again now, if any man is preaching to you a gospel contrary to what you received, he is to be accursed!"
The deception of these legalists in Galatia is easy to see. First, they persecuted Paul for teaching the true gospel of grace and then pretended he had changed his doctrine to entice the gullible believers into accepting a false gospel, which added circumcision to faith in Christ, as a requirement for salvation. But Paul gave a brilliant response: "But I, brethren, if I still preach circumcision, why am I still persecuted?" was his inspired answer. If Paul was teaching what the legalists claimed he would not be persecuted by them!!
However, the seriousness of his next sentence cannot be overlooked, for if circumcision was required for salvation, the very reason he was being persecuted was void - "for the stumbling block of the cross would have been abolished". But NOTHING, including circumcision, can be added to Christ's sacrifice on the cross, for in Christ Jesus neither circumcision nor uncircumcision means anything, but faith alone in Christ alone - working through love.
The eternal truth is that the cross is offensive to legalists - very offensive, because it insults the pride of those who want to make some sort of 'recompense' to God for their salvation - and having to accept salvation as a free gift is an affront to their vanity.
Heavenly Father, thank You for Your written Word and for the simple message of salvation - that it is Your free gift of grace, through faith alone in Christ alone as written in Your precious Word. Thank You that there is nothing I need to do to to procure my salvation other than believe on the Person and Work of Lord Jesus Christ, alone. Thank You that my salvation does not rest on what I have done but on what He has done on my behalf. Keep me, I pray, looking to Jesus alone in Whose name I pray, AMEN.