In order to answer this we will compare the portion you refer to with 1st Corinthians 6:9-11. We will quote each passage and see what we can learn.

Galatians 5:19-21 says, “Now the works of the flesh are evident, which are: ADULTERY, fornication, uncleanness, lewdness, idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies, envy, murders, drunkenness, revelries, and THE LIKE; of which I tell you beforehand, just as I also told you in time past, that THOSE WHO PRACTICE SUCH THINGS WILL NOT INHERIT THE KINGDOM OF GOD” (NKJV).

1st Corinthians 6:9-11 states, “Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor ADULTERERS, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God. And SUCH WERE SOME OF YOU. But YOU WERE WASHED, but YOU WERE SANCTIFIED, but YOU WERE JUSTIFIED in the name of the Lord Jesus and by the Spirit of our God.”

In Galatians 5:19-21 the apostle Paul is teaching us what he always taught; that “those who practice such things” will not inherit the kingdom of God. In other words, they will NOT go to heaven. In 1st Corinthians 6 Paul teaches the same thing in verses 10-11 but then he adds what the grace of God had accomplished in the lives of the believers at Corinth. Because they had been washed (Revelation 1:5), sanctified (Hebrews 9:14; 10:10, 14) and justified (Romans 3:24; 5:9) in the blood of Christ, they were no longer practicing the terrible sins enumerated here. Thus Paul could say of them, “Such WERE some of you.” Their faith in Christ had resulted in a great moral change of behavior and they are no longer looked upon as “fornicators, idolaters, ADULTERERS, etc.” Besides this, God sees the believer in an altogether new position “in Christ,” as we see in 2nd Corinthians 5:17, “Therefore, if anyone is IN CHRIST, he is a NEW CREATION; old things have passed away; behold, all things have become new.” God sees us in all the value of His beloved Son and His righteousness is imputed to us (see 2nd Corinthians 5:21).

I trust you have seen that an adulterer CAN BE FORGIVEN by trusting in Christ and that once they are forgiven they will no longer PRACTICE SIN. If they were an adulterer before their conversion to Christ they will forsake that wicked sin once they have been saved by God’s wondrous grace. In John 8:3-11 we have the story of the woman caught in the very act of adultery yet she turned to the Lord Jesus in faith and called Him “Lord.” Because she believed on Christ He told her, “Neither do I condemn you; go and sin no more” (verse 11). We have every reason to believe that the grace of God that saved her enabled her to no longer PRACTICE SIN. The Lord told her “go and sin no more” and we believe she abandoned her wicked life of adultery and that she lived a pure life to the glory of God. She, like some of the Corinthians, HAD BEEN AN ADULTERER, but that life ended the moment her heart was won to Christ, the One who eventually went to the cross and paid for her sin of adultery and every other sin she had committed. I would also encourage you to read John 4:1-30 and Luke 7:36-50 where we see two other women who both had bad reputations in their city (one for FORNICATION and the other for being A SINNER, which may refer to her being a PROSTITUTE). Their hearts too were won to Christ, and His love and grace compelled them to abandon their wicked lives and to follow their blessed Savior.

I would only add in closing that a true believer “may” fall into sin temporarily, even the sin of adultery. But it will NOT characterize them; in other words they will NOT continue to PRACTICE THAT SIN. If one does, it will prove that they were never really washed, sanctified and justified in the blood of Christ.  (350.2)  (DO)