It is because they don't really know our God. We really have to pray for all those who haven't known God's true love. It is kind of sad. There but for the grace of God, go us.
It is biblical prophecy:
John Chapter 15: 17-21
This I command you: love one another.
"If the world hates you, realize that it hated me first. If you belonged to the world, the world would love its own; but because you do not belong to the world, and I have chosen you out of the world, the world hates you. Remember the word I spoke to you, 'No slave is greater than his master.' If they persecuted me, they will also persecute you. If they kept my word, they will also keep yours. And they will do all these things to you on account of my name, because they do not know the one who sent me.
If you feel compelled to add to Christ, that's your prerogative.
Again I encourage you to return to the Bible and read for yourself there is only one name under heaven by which men are saved, Jesus Christ.