Psalm 64:6 (NIV)
Surely the human mind and heart are cunning
As long we hold on to any romantic notions that there is still an ounce of goodness left in us we'll never fully need or embrace Christ. The first thing that the Holy Spirit does is that He points out how morally depraved we are in the light of Christ. When the Spirit of God hits the lights our true self is exposed and there's no where to hide. This exposure of sin and rebellion against God is what causes us to become defensive or outright hostile when the gospel is first preached to us. Given the right opportunity, every one of us could have committed the crimes that we condemn others for. A saint knows who he is in the light of Christ and eternally grateful for the redemptive power of Christ. If our preaching is making us more friends than foes, then it may be lacking the convicting power of the Holy Spirit.