If believers sin, do they lose their salvation?

The Corinthians were very carnal Christians, living in sin which Paul says even the lost Gentiles did not practice (I Corinthians 5:1) yet Paul address them as “Saints” (I Corinthians 1:2). In I Corinthians 6:9,10 Paul writes the same statement as Galatians 5:21 to the Corinthians but follows it with the statement “And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God” ( I Corinthians 6:11). Their sinful practices are not seen by God. Those who will not enter the Kingdom of God are those yet in their sins – the lost. The same is true in Galatians 5:21. There Paul says “I tell YOU … THEY which do such things.” The YOU and THEY are not the same people. They are those who are “in” the flesh. Romans 8:9 says we are not in the flesh. Also, Paul uses that same expression as in Galatians 5:21 and I Corinthians 6:9,10 again in Ephesians 5:5 but in Ephesians 5:7 we see clearly that Believers are not who he was referring to in Ephesians 5:5.

Here is another interesting point. The Corinthians were living in gross sins and yet Paul never doubts their salvation. The Galatians began to add works to salvation and Paul says to them “I am afraid of you, lest I have bestowed upon you labour in vain …. I stand in doubt of you” (Galatians 4:11-20).