I'm currently in a debate regarding this topic and i'm currently stuck with where they are citing Gal 2:16 www.biblegateway.com
Any help would be appreciated.
I have already referenced James 2:24
and the following taking from John Martignoni from http://www.biblechristiansociety.com
Rom 11:17-23, “But if some of the branches were broken off [the Jews], and you, a wild olive shoot [the Gentiles], were grafted in their place to share the richness of the olive tree [Jesus Christ], do not boast over the branches...For if God did not spare the natural branches, neither will He spare you...Note then the kindness and the severity of God: severity toward those who have fallen, but God’s kindness to you, provided you continue in His kindness; otherwise you too will be cut off.”
Paul is talking about how salvation has come to the Gentiles, while many of the Jews have rejected it. And he makes it very clear that once you have been grafted into Christ, you must “continue in His kindness,” or you can also be cut off. So, even after you’ve been saved, you can still be cut off from Jesus Christ.
This is further seen in Galatians, chapter 5. Verse 1, “For freedom Christ has set us free; stand fast therefore, and do not submit again to a yoke of slavery [sin].” If once saved always saved is true, then one cannot “submit again” to a “yoke of slavery,” and Paul’s warning makes no sense.
But Paul goes on in verse 4 to say, “You are severed from Christ, you who would be justified by the law; you have fallen away from grace.” Paul is talking to Gentile Christians who had been wrongly taught by the Judaizers that they have to be circumcised and obey the Mosaic Law in order to be true Christians. Paul tells them that is false, and if they submit to circumcision and to the Old Law, they will be “severed from Christ.” If once saved always saved is true, though, they can’t be severed from Christ and, once again, Paul’s warning is meaningless.
We also have the Parable of the Prodigal Son, Luke chapter 15. The Prodigal Son was in his father’s house, and the father here is representative of God the Father. Then, the Prodigal Son leaves his father’s house and goes and lives a sinful life. In the end, though, he repents and returns to his father. After the Prodigal Son returns, the father says this of him in verse 24: “For this my son was dead, and is alive again; he was lost, and is found.” Notice very carefully, though, that the father says the son is alive “again.” In other words, the son was alive, or saved, when he was in his father’s house at the beginning of the parable; was “dead,” or unsaved, when he left his father’s house and lived in sin; then was alive again, saved again, when he repented and returned to his father’s house. Alive, dead, alive again. Saved, unsaved, saved again.