Okay, I see what you meant now. But I still have to question when sex outside of marriage "became" a sin. Most of the notable men in the OT had as many concubines as they could afford- sex outside of marriage but not seen as a sin. Multiple wives in the time when Jesus lived- how could having multiple wives not be considered sex outside of marriage? Wouldn't the first wife be the only true wife and the rest not?

Solomon had (if the story in the OT is true) 900 concubines- sex outside of marriage and that was fine with the Hebrews (they weren't called Jews until the diaspora when they were released by the Babylonians and returned home).

Even Paul said it was best that deacons be the husband of only one wife but that wasn't required so weren't the deacons who had more than one wife committing sex outside of marriage? I don't see the difference and neither did people of Jesus' time and all the many centuries before that. Any man, married or not, could have sex with whomever he chose and that was common practice. And it wasn't considered a sin.

Sex outside of marriage suddenly became a "sin" in the 4th or 5th century because the Church decided it to be "sinful" and thus it might block you from bring "saved" by Jesus.

There were and are many things the Church decided are "sins" but that didn't stop Church leaders from engaging in greed, gluttony, theft, lying, pederasty, torture and murder, all in the name of God. It was one more thing the Church used in an attempt to gain even more power and money and control over the largely illiterate masses.

Sex outside of marriage pales in importance beside those things and I'm not sure why anyone else would see it as a sin but neither is it something I'd recommend. Nor would I condemn anyone for indulging it because I'm not fit to judge anyone other than myself.