The blog below elaborates upon these main points:
Proponents of same sex marriage believe that all desires are equal and good to act upon and that this is the defining aspect of humanity.
The Gospel proposes that the measure of humanity is Jesus: who, though tempted in every way like us, never acted on any evil desires nor justified unlawful sexual behavior. Indeed, he made it clear: sexual desire is not what identifies people, but rather the image of God. Essential to the image of God is the defeat of evil.
If we call evil good and good evil, as members of the homosexual lobby encourage us to do, we put ourselves under the judgement of God. So while we are not to condemn those who do evil by lashing out at them in rage, we must not identify with the cause of evil.
Lord, have mercy.