Why is same sex marriage so wrong according to Christians?
Marriage, The strongest relationship between humans in union with God. This union, or covenant created by God is considered a sacred union by God's word. A union between a man and woman. In the book of Mathew, Jesus teaches us this;
And He answered and said to them, "Have you not read that He who made them at the beginning 'made them male and female,' and said, 'For this reason a man shall leave his father and mother and be joined to his wife, and the two shall become one flesh'? Mat. 19:4-5
Christians hold to this truth of this union between 'male and female'. Not male and male. Not female and female. What God has ordained to be a "natural relationship", man and his secular view has twisted it to be what ever he justifies. This subject, as you may know is one of the most controversial issues today. Regardless of the debate, God's word, the Bible is and has been the consistent truth that Christians hold to.
The allowance of same sex marriage is the acceptance of homosexuality which the Bible explicitly prohibits. Both in the Old and the New Testaments;
You shall not lie with a male as with a woman. It is an abomination.” Lev. 18:22
Do you not know that the unrighteous will not inherit the kingdom
of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor
homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers,
nor extortioners will inherit the kingdom of God. 1 Cor. 6:9-10
God's word has been made know to us in clear language. His truth in all things;
"because what may be known of God is manifest in them, for God has shown it to them. For since the creation of the world His invisible attributes are clearly seen, being understood by the things that are made, even His eternal power and Godhead, so that they are without excuse." Rom. 1:19-20
However, as time goes on, man, in his natural fallen state who's very nature which is to resist the things of God, has allowed unnatural relationships to become common place;
For this reason God gave them up to vile passions. For even their women exchanged the natural use for what is against nature. Likewise also the men, leaving the natural use of the woman, burned in their lust for one another, men with men committing what is shameful, and receiving in themselves the penalty of their error which was due. Rom. 1:26-27
It is to these truths, that Christians hold what is righteous.