 Because it's pleasure for a season. That's what Hebrews chapter 10 says. And there's a lot of Christians that are backslidden because they're living in sexual sin. Because in the flesh, there is pleasure for a season, but they forget about the flip side, the enemy's trap to that. That it devastates families, it destroys lives, it produces unwed children, children often moves into unnecessary abortions, and it even produces venereal disease and other diseases.