I'm not Christian first of all

But I really want to know why, things like sex or touching your self is a sin??

I totally respect your opinions and beliefs, but I still want to understand and learn why intimacy is so wrong and "dirty" ??

I once saw a documentary and the Christian man (he was a preacher I think) said that anyone who commits sexual acts is the equivalent of a "dirty tooth brush" ....

What's so wrong about it?..

Insight would be really appreciated

Thanks all ❤️