That’s always been a weak argument to me, the best explanation I was ever given was in Catholic School.
It was the fact we were made in God’s Image and God Created (Designed) us.
Women was specifically designed for Man (Adam) and this is the natural design.
Man and Woman were meant for each other, designed for each other. Anything outside of this was an insult to God’s design for us (sometimes referred to the natural order)
Sinning against the natural order is a hate crime against God in other words.
The institution of marriage was also established by God to illustrate the relationship God wants to have with man. Not in the physical sense, but in the spiritual sense of unity.
Immoral physical union undermines the spiritual union which God intended as a message to mankind that He loves us, and that we need Him.
Salvation is the choice to be unified with God through His Son Jesus Christ.
If we refuse to repent of sin (including homosexuality), then it is simply not possible to make that choice to receive His gift.
Amen to that.