Agreeing with the Family Research Council on this issue at least in terms of whether or not "same-sex" marriage is right or wrong (it's wrong) doesn't constitute a statement of full agreement with them in all matters. For instance, I am anti-war (including what is termed "just war"). I am also anti-capitalism, per se. Most importantly, I am anti-coercion as much as that is humanly possible -- very difficult.
The only place Jesus employed what might be deemed coercion was when he cleansed the temple of the money-changers. Of course, that temple was a voluntary place to be. At least it was supposed to be. It makes a difference. If you want to be with God and Christ, don't expect not to be rejected if you refuse to conform to the house rules. No one is dragging you into that house. In fact, very few people ever even discover the entrance.
Now, if the whole nation and the whole world become Heaven on Earth, we won't have to face these decisions. Everyone will have voluntarily chosen to do the right things, the Jesus-like things.
What Jesus made clear is that marriage is between a man and a woman, not a man and man or a woman and a woman.
He held that way for pretty much exactly the reasons stated in the video below: Sex (becoming one flesh) is first and foremost for procreation. The more that sex runs contrary to that first-principle, the more it is anti-human, frankly, the less enlightened it is, the more it comes out from the darkside and will serve to destroy rather than build up.
And he answered and said unto them, Have ye not read, that he which made them at the beginning made them male and female, And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one flesh? Wherefore they are no more twain, but one flesh. What therefore God hath joined together, let not man put asunder. (Matthew 19:4-6 KJV)
People can attempt to twist that or to diminish it or ignore it, but none of doing that will alter the true import of Jesus's sage heterosexual-marriage affirmation.