Immediately the boy’s father exclaimed, “I do believe; help me overcome my unbelief!” -Mark 9:24
We relate to this. We have belief, but we also know we have doubts at times. Like us, this man was concerned about his unbelief, his doubts. Do I have enough faith? Remember though, Jesus simply cast the demon out not because the man's faith was "good enough" but because he believed. Perfect belief? No. But he believed. I want my faith to grow, but I'm also glad that I have faith. Sometimes, just a mustard seed's worth is enough.