Sola Gratia is the Doctrine that states we are saved by grace alone.  Adding anything to that drains the Gospel of its Power.  Paul and Barnebus returned to Antioch to confront some recent Judiazers who stated that you needed to be circumsized to be truly a Christian.  This is called Legalism. Genesis 17:14 does indicate the early Jews were required to be circumsized, but even following all the laws they could not be perfect and would never enter the Kingdom of God. The Old Testament teaches about the one who will come which will take on the burden of our sins and die on the Cross for us.  Only through Gods Grace can we be saved.  No acts we do can accomplish this.  Paul and Barnebus went to Jerusalem to address the problem of Judiazers who said they were Christians, but indicated the gentiles needed to be circumsized.  In Deuteronomy 30:6 - It states the Jesus, the Lord your God will circumcise your heart.  He will take on our burdens of sins and cleanse our heart.  James the half Brother of Christ agreed that once God called them (Gentiles) clean, let no one say they are Common (Unclean).  This helped the Christians Church to better be able to deal with the different cultures between the Jews and Gentiles and to become a unified Church under God.  We need to be careful to not bring Legalism into our treatment of other culters and people who also trust and believe in the Lord.  Be careful of Political Legalism, Cultural Legalism and Ritual Legalism which will bring in any additional requirement or distraction from us reaching the unsaved or working with those who are saved, but have a different culture/custom that we are not comfortable with.  It is God who Save us through Grace.