Can a person lose salvation? No. The two, you see, are not the same thing. Grace is favor or undeserved kindness. Can we fall out of favor with God? Certainly. We do with every sin. But repentance restores our relationship with God.
Can we lose salvation through sin? No. Salvation is God’s doing not ours and we can’t lose what isn’t ours.
The confusion which equates falling from grace with loss of salvation is easily corrected when we recall that falling out of favor is not at all the same thing as losing salvation.