It sounds a little chicken and egg ish, which one inspires the other? if someone is interested in God but come to church and see a poor programme because of a lack of effort, their interest in God may be affected because of the poor example of church goers. Or if the programmes have little relevance to the person searching, even though they may have an interest in God, the church may be if little benefit to them.
Let me give you a sporting example, I love sports especially cricket and would probably watch all types from the very exiciting T20 cricket to rather dull and sometimes boring 5 day test cricket. I appreaciate the skills involved in both type and believe both are relevant for the sport of cricket. Now if you have someone who dosen't like cricket or hasn't really watched it, which one would you introduce them too?
I think sometimes its very similar to church life, most young person live a fast-paced life, on the go all the time soaking up information from all around, we then expect them to come to church and "fit in" to the normal service (probably more aligned to a 5 day test match rather than a 2 hour T20 match!!) While some may appreciate it, it is so out of step from reality that they would rather not attend church and look to get their spiritual "high" from somewhere else.
Why do they leave? church (not God) offers no relevance to them.