When a person says that, “You must repent, meaning that you have to stop sinning and then believe on Christ for your salvation,” stay away from that.
There’s a misunderstanding. Genesis 6:6 shows that God repented.
Does that mean that God turned from his sin, stopped sinning?
Obviously, it simply means a change of mind.
Jonah 3: 8,10 – If that definition applies to turn from your sins, God sees that as works.
Obviously Christians are not saved by works, but by faith, only in the Lord Jesus Christ, a person starts to repent as a sinner.
What they do is that they don’t stop sin themselves.
When they repent as a sinner, they simply believe on Jesus Christ.
They turn to God to get rid of their sin problem for salvation.
They don’t stop sinning first. Notice Acts 20:21 shows repentance toward God and faith toward our Lord Jesus Christ.
For more information, read this article on debunking Lordship salvation.