Before I go any further in this discussion, let me say that it's not all the church's fault why people don't attend church. Sometimes it's the issue of the would-be attender. And sometimes it's not the fault of either. It's just the result of a busy world with too many things to do.
Also, let me clarify something. When I talk about "attending church", I'm simply talking about a Sunday service. "Church" is much bigger than that. In reality, "church" is a community of people that have committed their lives to obeying Jesus together. But for the sake of this discussion, I'm reducing the meaning of church to the Sunday service because that's what most people think of when they hear the word and that's the most common entry point into the community.
Given that definition, another reason that people don't attend church is that there is too much competition for that time slot. When I think of our "competition" on Sunday morning, I never think of another church. We're not competing for people to attend our church over another. We are competing with things like...sleeping in, coffee and the Sunday newspaper, fishing, golfing, house chores. There are only so many hours in the week and most of us have more on our "to do" list than we have time to do them in.
Many people can't justify taking a couple hours of valuable time to participate in something that they see no immediate return on their investment. In two hours I can play nine holes, or put in a garden or get the paper read! Church will always be there. It's not as urgent a need as the others are.
Lesson: Churches need to make their Sunday service valuable. Now, in theory, you shouldn't have to do that for church members, people that are committed to the community. Members should gather for the same reason that a family gathers for a meal - to build relationship (not the gourmet meal). But I"m not talking about the committed. I'm talking about the person that is considering church attendance.
There are three things that I've seen people attracted to... a chance to build relationship, music that helps them connect with God and a message that helps them to be a better person - whether that's understanding God better, or other people or themselves. If a person is convinced that attending a church service will make their life better in some way, they'll make time for it. If they perceive that church attendance is a time waster, a mere religious formality, then their pragmatic side takes over and they stay home. That might seem selfish, but remember, I'm not talking about committed believers. I'm talking about that individual who is assessing how they should spend their time. They don't have any connection that makes them feel obligated to attend. In fact, it's their other life obligations that make them want to stay home.
The reality is that most people won't venture into a church until they have a pressing concern... they want to expose their children to God, their marriage is failing, they have lost a sense of purpose, etc. They suddenly feel vulnerable and are looking to see if God can meet them in their weakness. For this reason, it's imperative that churches offer these seekers an experience that impacts them for good and not a social club or meaningless religious formality. In many cases, they'll only give you one chance. I wish that wasn't the case but it is. They need to walk away saying, "I'm glad I came. I needed that. I need to return for more."