Paul, an apostle of Christ said this.... "It isn't my responsibility to judge outsiders, but it certainly is your responsibility to judge those INSIDE [emphasis mine] the church who are sinning." (1 Corinthians 5:12)
There IS s judgment which we, as Believers, are to honor. That is. ...to call other Christians to pursue holiness. To right another...when another Follower is living, doing, outside the precepts of God's will. We cannot judge anyone outside the church. They do not, cannot, have the same mind and will of Christ. Simply, they have not made s decision to do so. Therefore, any "judgment" brought by people is outdide of God's intent, and certainly outside of our ability. Only God can, and will, provide judgment. Believers are, biblically, to hold one another accountable. (Hebrews 10:24-25, Proverbs 27:17).
What Christianity can, and should, do is to "love thy neighbor", to not stand in judgment, but to express a warning, a truth, of how Almighty God views sin. We obtain that truth, in context of the whole, from scripture.
If Christ-followers are judging those who have not accepted and believed in Jesus Christ as Lord and Savior ...they are taking on a role for which they are not equipped, are not authorized, nor commanded.
We ARE commanded to go into the world, to preach the saving gospel truth to all who will hear it, and to baptize Believers (Acts 1:8, Mark 16:15). It stands to reason that a Christ-follower would warn an un-believer about his/her sin, and lostness, short of Jesus Christ. And if we approach an un-believer about sin without expressing the grace if Christ ...we are in error; great error.
We ARE called to agree with God about sin. That is, if God calls a thing "sin" it is disobedient of us, as followers, to attempt to white-wash it or call evil good (Isaiah 5:20). Scripture classifies homosexuality, among other things, as sin (see this explanation at http://www.gotquestions.org/homosexuality-Bible.html).
Conclusively, as Christ-followers, we must agree with what God says about the thing. Yet, we cannot place, or pass, judgment on a non-believer. We cannot because we cannot expect those without Christ in their lives to even begin to behave as one redeemed by Christ; a gift which is made available to all, by God's grace, through Christ (John 3:16).
Christianity cannot condone the sin of homosexuality. Christianity cannot agree with it. Christianity cannot call what God calls sin ....anything otherwise. God's word, in all contexts, is clear.
We ARE called to love. To love our neighbor, to love those without Christ into a loving, forgiven, relationship with Him ....and to trust in the work of The Holy Spirit to change that person so that they too will agree with God, and His Holy word, about sin.
Christians are the guides to the only One who "can" redeem; the One who has already performed the work to do so. Following, believing ...that is up to you. We are the messenger, the bringer of good news, of hope. Not better. Just surrendered.
Let us be clear. We CAN love the sinner, and despise the sin itself. Why? Because of love. It is the Christians' desire that you be set free from what God calls sin, just as we were! How awful, how selfish, how mean, how hypocritical would we be if we didn't desire that you, too, avoid the self-condemning folly of rejecting Jesus Christ as Lord, as Savior. Whether you think that is true or false ...is a different matter altogether. And God gives us ALL (meaning, every human) the freedom to believe, or to not.
When we speak ..it should be, in love.
"If I could speak all the languages of earth and of angels, but didn't love others, I would only be a noisy gong or a clanging cymbal. If I had the gift of prophecy, and if I understood all of God's secret plans and possessed all knowledge, and if I had such faith that I could move mountains, but didn't love others, I would be nothing. If I gave everything I have to the poor and even sacrificed my body, I could boast about it; but if I didn't love others, I would have gained nothing. Love is patient and kind. Love is not jealous or boastful or proud or rude. It does not demand its own way. It is not irritable, and it keeps no record of being wronged. It does not rejoice about injustice but rejoices whenever the truth wins out. Love never gives up, never loses faith, is always hopeful, and endures through every circumstance. Prophecy and speaking in unknown languages and special knowledge will become useless. But love will last forever! Now our knowledge is partial and incomplete, and even the gift of prophecy reveals only part of the whole picture! But when the time of perfection comes, these partial things will become useless. When I was a child, I spoke and thought and reasoned as a child. But when I grew up, I put away childish things. Now we see things imperfectly, like puzzling reflections in a mirror, but then we will see everything with perfect clarity. All that I know now is partial and incomplete, but then I will know everything completely, just as God now knows me completely. Three things will last forever—faith, hope, and love—and the greatest of these is love." (1 Corinthians 13:1-13)