Attitudes Hindering Religious Experience and Christian Belief
First, the offer of salvation through Christ is free; it cannot be earned. This offends our desire to earn what is most important to us.
Second, the gospel calls sinners to repentance. The message of Christ and his Apostles is inherently humbling to the prideful ego. We may chafe at this.
Third, the way of Jesus is the way of the Cross and of personal sacrifice for Christ and the Kingdom of God. The Cross asks for our all and warns us of the costs therein—but always with the promise of God's presence and ultimate vindication in view. Many would rather (try to) control their own lives as “captains of their own ship.”
These ideas are culled from John Stott's Why I am a Christian, but I cannot find the page number!