Have you noticed that one of the constant attacks on Christianity is the violence done in the name of Jesus? Wars, attacks, or just being a jerk in particular. That’s actually more of a judgment against man than Jesus.
Just a shallow reading of any of the Gospels reveals the contradiction between his teaching and people’s behavior. Every sin has its roots in at least one of three things; greed, power, and lust. We’ll twist anything good to justify our sin, or take a good thing to an extreme that it should not be.
It doesn’t invalidate Christ but proves the need for Him.
Look at things like ‘conversion by concussion’, where people move into a country to gain power under the banner of the Great Commission. It’s a contradiction. The only two people absolutely sure of your repentance and following Jesus is him and you. All else is only appearances because no man can see into another’s heart.
Killing in the name of?
Listen…‘turn the other cheek’, ‘vengeance is mine, I will repay’ ring any bells? What about love your neighbor? Even when Jesus goes to war at the end of the world against the forces of evil, he’s the only one killing people (Rev:19:11-21)
Zeroing in on a particular sin, and beating the warning drums for it only? They’re all bad, break one, break them all (James 2:10-13). All have sinned and fallen short of the glory of God. Our goal is not to condemn, but to reconcile first ourselves to God, and then others. Any conviction they should feel is the Holy Spirit as He points out the sins.
When man uses God for his own means, rather than being used by God, it doesn’t invalidate anything. It displays the need for the Cross to purify and clean the heart of man.
A Ronin's Journey 