“If I’m saved, where are the daily doubts coming from?”

I continue to struggle with pornography. What can I do differently? Did Enoch and Elijah get a special death-free experience from God? I know I’m saved, but for some reason I still get the doubting thoughts. Where is that coming from? Is it okay that I was saved without anyone else present? Are the Canaanites descendants of Cain? How would they be alive after the flood? Can you explain sanctification, holiness, and perfection (completeness) in Christ?