Growing in faith- we can't do it on our own

Mark 9:24  "Immediately the boy's father exclaimed, 'I do believe; help me overcome my unbelief' "

The boy's father was pleading with Jesus to rid his son of the demon possessing him.  The father had previously made the statement to Jesus, "But if you can do anything,...", to which Jesus responded, "Everything is possible for him who believes."  What the father says above seems to be contradictory, on the surface.  How can you believe and at the same time ask for help overcoming your unbelief?  Isn't belief an either-or proposition? 

This might be true if belief and faith were a willful human act, but I don't believe they are.  Belief and faith in God are a gift of the Holy Spirit, and the Spirit allows us to grow in belief and faith.  All we can provide is  receptiveness, and the Spirit does the rest.  The father's statement, then, is actually quite insightful.  He expresses his receptiveness to the Spirit by saying, "I do believe".  Then he asks the Holy Spirit to come to him and do the job he as a man is incapable of- growing and developing true belief and faith.