Many people, including Christians think that they do good by not speaking out against sin(homosexuality, divorce&remarriage, abortion, lust, etc..)
But it's wrong to NOT speak out against it. It is wrong to accept sin, it's wrong not to hate sin, and it's definitely wrong to defend sin.

Psalm 97:10
Ye that love the Lord, hate evil: he preserveth the souls of his saints; he delivereth them out of the hand of the wicked.

Romans 12:9)
Let love be without dissimulation. Abhor that which is evil; cleave to that which is good.