Elders are called to protect the church from people who would do them spiritual harm (wolves among the sheep). One of the ways we try to do that in our church is by not allowing people to get very involved in the life of the congregation until they are members.
So in our church, non-members are welcome to attend and participate in the public services of the church. We are happy to have them in our Sunday morning gathering, our Sunday evening gathering, and our fellowship meals.
(I've revised this to try to be more concilliatory and show my reasoning from Scripture more. Thanks for comments that pointed out that my post had not been very humble. I'm attempting to be provocative (I genuinely think this is an important topic where we may be putting unecessary burdens on children). I hope also to be gracious.)
I like the seven hopes of the pastors. At MVBC we also have a four-week class for people interested in membership. Much like you set the stage with those seven hopes, we begin with a couple principles that are biblical and essential for church life.