A surprising number of my friends on Facebook changed their profile pic to this photo. I guess the number itself wasn't so surprising as the number of them whom I would've assumed considered themselves Christian. Even Rob Bell, the famous evangelical minister known far and wide openly supports gay marriage.
Support the lifestyle of practicing homosexuality or support the teachings of the Bible—you can't do both. The Apostles, inspired by God and acting to spread the word about Jesus Christ, powerfully condemned the continual practicing of homosexuality alongside every other sin us humans get involved in.
"Don’t you know that those who do wrong will have no share in the Kingdom of God? Don’t fool yourselves. Those who indulge in sexual sin, who are idol worshipers, adulterers, male prostitutes, homosexuals, thieves, greedy people, drunkards, abusers, and swindlers—none of these will have a share in the Kingdom of God" (1 Corinthians 6:9-10 1 Corinthians 6:9-10  Know you not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind,
 Nor thieves, nor covetous, nor drunkards, nor revilers, nor extortionists, shall inherit the kingdom of God.
American King James Version×, New Living Translation, emphasis added).
Paul wrote that to a church that was surrounded by a culture way more sinful than ours in the West today—temple prostitution was still a thing back then. But Paul and Barnabas and the other apostles were not afraid to go in and strongly condemn all those practices as what they were—sinful and despised by God. To be clear, there is a distinction between somebody who is homosexual (they have same-sex attraction, you might call it) and somebody who practices homosexuality. The former is a trait that is ingrained in somebody's state of mind, the latter is choosing to accept that way of life and practice it.
To those Christians who change their profile picture in support of "marriage equality," I say, "Stand for something, you gutless hypocrites." Or to quote Jesus when He rebuked the religious people of His day, "You hypocrites! Isaiah was right when he prophesied about you: ‘These people honour me with their lips, but their hearts are far from me. They worship me in vain; their teachings are but rules taught by men’” (Matthew 15:7-9 Matthew 15:7-9  You hypocrites, well did Esaias prophesy of you, saying,
 This people draws near to me with their mouth, and honors me with their lips; but their heart is far from me.
 But in vain they do worship me, teaching for doctrines the commandments of men.
American King James Version×, Isaiah 29:13 Isaiah 29:13Why the Lord said, For as much as this people draw near me with their mouth, and with their lips do honor me, but have removed their heart far from me, and their fear toward me is taught by the precept of men:
American King James Version×, NIV). If you say you follow Jesus Christ, but don't have the guts to actually practice that way of life or support its teachings, then admit you are not a Christian. Will you join the next movement that seeks to legalize extortion? Will you change your profile picture in solidarity with shoplifters when the movement to legalize stealing comes around? Do you think it's OK to cheat on your spouse?
Be a Christian or don't. There is no in-between. Saying you follow Jesus Christ but supporting something like gay marriage is using His name in vain. It's an affront on His perfect, righteous character. It's an insult to God, who offered His Son so we all could have salvation from death (John 3:17 John 3:17For God sent not his Son into the world to condemn the world; but that the world through him might be saved.
American King James Version×). And let's not forget that accepting that sacrifice then willfully and purposefully sinning is what you might call the unpardonable sin (Hebrews 10:26-27 Hebrews 10:26-27  For if we sin willfully after that we have received the knowledge of the truth, there remains no more sacrifice for sins,  But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
American King James Version×).
Hope for All of Us Sinners
Here's Paul's follow-up point to his condemnation: "And that is what some of you were. But you were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and by the Spirit of our God" (1 Corinthians 6:11 1 Corinthians 6:11And such were some of you: but you are washed, but you are sanctified, but you are justified in the name of the Lord Jesus, and by the Spirit of our God.
American King James Version×, New International Version). This is the scripture that many have called the most hopeful verse of the Bible. It shows that even in a society which was super pagan and sinful, a church made up of individuals called out of that mess could come to repentance and change. They could each look at their lives and recognize all the bad influences society had had on them, and decide to bury that old person. Put on the new man. Put on the mind of Christ. Live a life showing fruits worthy of repentance (Colossians 3:9-10 Colossians 3:9-10  Lie not one to another, seeing that you have put off the old man with his deeds;  And have put on the new man, which is renewed in knowledge after the image of him that created him:
American King James Version×, Romans 12:2 Romans 12:2And be not conformed to this world: but be you transformed by the renewing of your mind, that you may prove what is that good, and acceptable, and perfect, will of God.
American King James Version×, Philippians 2:5 Philippians 2:5Let this mind be in you, which was also in Christ Jesus:
American King James Version×, Luke 3:8 Luke 3:8Bring forth therefore fruits worthy of repentance, and begin not to say within yourselves, We have Abraham to our father: for I say to you, That God is able of these stones to raise up children to Abraham.
American King James Version×, Isaiah 1:16 Isaiah 1:16Wash you, make you clean; put away the evil of your doings from before my eyes; cease to do evil;
American King James Version×).
All of us are in the same boat—we all sin, we all fall short (Romans 3:23 Romans 3:23For all have sinned, and come short of the glory of God;
American King James Version×). We all must repent and live a life showing fruits worthy of repentance. Let's not get caught up in the popular movements that seek to distract us from our calling. Let's not let our clear vision of God's coming Kingdom be blurred by the slow and sure progression of human nature's influence. Let's put away our old, sinful ways and live a new life of righteousness and holiness (Ephesians 4:20-24 Ephesians 4:20-24  But you have not so learned Christ;  If so be that you have heard him, and have been taught by him, as the truth is in Jesus:  That you put off concerning the former conversation the old man, which is corrupt according to the deceitful lusts;  And be renewed in the spirit of your mind;  And that you put on the new man, which after God is created in righteousness and true holiness.
American King James Version×).