One of the most trendy things to say nowadays is "Don't judge me!" or "You don't have the right to judge another person!"  Well, the world can surely believe whatever it wants, but if you believe those things, then don't claim to be a Christian, or say that you love Jesus, because God has made his position clear on this subject:

Leviticus 19:15
Ye shall do no unrighteousness in judgment: thou shalt not respect the person of the poor, nor honor the person of the mighty: but in righteousness shalt thou judge thy neighbour.

John 7:24
Judge not according to the appearance, but judge righteous judgment.

Psalm 149: 6-9
Let the saints be joyful in glory: let them sing aloud upon their beds. Let the high praises of God be in their mouth, and a two-edged sword in their hand; To execute vengeance upon the heathen, and punishments upon the people; To bind their kings with chains, and their nobles with fetters of iron; To execute upon them the judgment written: this honour have all his saints. Praise ye the LORD.

I Corinthians 6:2
Do ye not know that the saints shall judge the world? and if the world shall be judged by you, are ye unworthy to judge the smallest matters?

I Corinthians 2:15
But he that is spiritual judgeth all things, yet he himself is judged of no man.

Proverbs 2: 6-9
For the LORD giveth wisdom: out of his mouth cometh knowledge and understanding. He layeth up sound wisdom for the righteous: he is a buckler to them that walk uprightly. He keepeth the paths of judgment, and preserveth the way of his saints. Then shalt thou understand righteousness, and judgment, and equity; yea, every good path.

Acts 10:42
And he commanded us to preach unto the people, and to testify that it is he which was ordained of God to be the Judge of quick and dead.

Psalm 37:30-31
The mouth of the righteous speaketh wisdom, and his tongue talketh of judgment. The law of his God is in his heart; none of his steps shall slide.

Luke 12: 54-57
And he said also to the people, When ye see a cloud rise out of the west, straightway ye say, There cometh a shower; and so it is. And when ye see the south wind blow, ye say, There will be heat; and it cometh to pass. Ye hypocrites, ye can discern the face of the sky and of the earth; but how is it that ye do not discern this time? Yea, and why even of yourselves judge ye not what is right?

God has commanded us to judge righteous judgment, and to preach to people that Jesus will one day be their ultimate Judge.  The only question is, whose judgment is correct?  Who's to say what can be judged good or bad?  The only answer is, God.  In the Bible, God has laid a final word on issues.  He's told us right and wrong, and told us how to live.  Our job is to believe him, follow his word, and help others to do the same thing by explaining their need to turn from sin and turn to the forgiveness that only Jesus can give.

Any judgment that we make must be based in God's word.  It's simple.  We can't rely on our own opinions or ideas, or on what's "politically correct."  We need to rely on God and trust that his judgment is the only judgment that will stand.  So in reality, we're not making these judgments on our own, we're merely telling people about God's judgment.  When I say "homosexuality is a sin," I'm not saying that it's wrong in my opinion.  I'm saying that God says it's wrong.