If you've never read anything on the connection between Baptism and Church Membership (or even if you have), then read this:
It is possibly the best article I've read so far on this issue (ok, I admit---not many). One that is probably just as good is Wade Burleson's on the matter (and of course, John Piper's, to which he links):
I do not agree with paedobaptism, and I believe it to be doctrinal error. However, I would not exclude a paedobaptist brother from church membership or participation in the Lord's Supper on that basis, though I would (as would John Piper) exclude that person from church leadership. But, I am not in a position of church leadership, so this is simply a stated opinion on my part. The union we have in Christ, and the spiritual baptism we share in the Holy Spirit, is far more important than the physical sign of water baptism or political union in the local body of believers, I think. Those in the SBC who would refuse membership and the Lord's supper on these grounds are forgetting the membership and baptism which is in Christ.
It just strikes me as odd, like a bunch of children telling one of their own, "We like you. We'll even let you play with us in our treehouse. You just can't join our club."