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.
That’s all true, but this is how it was explained to me in the second grade without any kind of sexual act involved in simple terms.
It explains the basis for these other explanations to build on.
The new generations demand to know deeply why something is important, otherwise they will dismiss it as not important and outdated.