I just can't envision a Christian denying Jesus Christ and turning to Izlam...
Apparently you are trying to make a point but if you can't argue the point from scripture, you don't have a point...
Are you saying it’s impossible - would never happen ever under any circumstances?
Does it really make sense that one time mumbling “Yeah, Jesus Christ, my personal Lord and Savior, whatever” forgives any and all sins, no matter how depraved?
If that’s the case, why did not Jesus Christ say “Forget the 10 Commandments, this is a New Covenant, accept Me as your Personal Lord and Savior, and then you’re free to do whatever you want with no adverse consequences”?