"Then said Jesus unto his disciples, If any man will come after me, let him deny himself, and take up his cross, and follow me. For whosoever will save his life shall lose it: and whosoever will lose his life for my sake shall find it. For what is a man profited, if he shall gain the whole world, and lose his own soul? or what shall a man give in exchange for his soul?" (Mat 16:24-26)
I think one thing, more than almost anything else that keeps people from faith in Jesus is the desire people have to be in control of their own destiny. So often people take the attitude that God is going to spoil the fun by making them do a bunch of religious stuff, stop doing what they are doing, give up this or give up that, etc. That goes against the desire to have control over their lives.
I often wonder how many people in church are doing the same thing. It seems they are just trying to control their destiny by earning a ticket to heaven while still being in control of the day to day things of life. Probably quite a few.
In most cases that attitude can only change when they encounter some crisis in life that is beyond their ability to control. Once the illusion that they can control everything in their lives is gone, the idea of a spiritual power greater than man starts to sound more appealing.
The statement by Jesus that we must deny the self is one of the more difficult teachings of Jesus to explain to people. To follow Jesus means to give up control over your life and be led in all things by the Spirit. It's that "dying to self" thing and it is often confusing to people why someone would do that. It is difficult to explain that living by faith in that power leads to something better than what they think they can achieve on their own power.
Over time, the anxiety, bitterness, and frustration at the things of this world eventually get displaced with a profound sense of peace. On top of that, there are undiscovered talents, gifts, and capacities that begin to emerge. But, until a person has been on that road for a while those advantages aren't obvious and it is difficult to convince people that it can and will happen.