In this "battle" of two of our theological giants, Grudem has struck back, but admits his wife is on Piper's side on this one!

I do not see denial of church membership as “virtually the same as excommunication,” nor do any of the Baptist churches known to me. Non-members who are clearly believers in Jesus Christ are welcomed as believers into many aspects of fellowship. They share in the Lord’s Supper together with members (in all but a very few of the most strict Baptist churches). They participate freely in worship and prayer and fellowship. Sometimes a Baptist church will even have a Bible-believing Presbyterian or Episcopalian or Methodist or Lutheran pastor preach as a guest from the pulpit. That is far from “excommunication”!

. . . There was an unexpressed assumption in my discussion, an assumption which your response makes clear to me. I did not express it because it is so commonly assumed in nearly all churches. The assumption is this:

Baptism is required for church membership.

I think I assumed this because, as far as I know, it has been the practice of all major denominations throughout history. Presbyterians believe that baptism is necessary for church membership (for they consider infant baptism true baptism). Episcopalians believe that baptism is necessary for church membership. Baptists believe that baptism is necessary for church membership. Pentecostals believe that baptism is necessary for church membership. Methodists believe this. The Evangelical Free Church of America (which allows both views of baptism) believes this. Independent Bible churches believe this. Even Roman Catholics and Eastern Orthodox churches believe this. Apart from some unusual groups that don’t practice baptism at all (such as the Salvation Army), I think that the whole church throughout its history has held that baptism is necessary for church membership.

. . . I think the reason churches throughout history have required baptism for membership is that the New Testament so clearly makes baptism the public act that every believer undergoes at the outset of the Christian life. It is right there in the Great Commission: “Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you” (Matthew 28:19-20). There is no such thing in the New Testament as an unbaptized person being an active member of any local church. So how could we say today that we should start allowing unbaptized persons to be members of our churches? But that (it seems to me) is what my earlier position, and your current position, would have to say.

I do not think such a position is wise, or consistent with the New Testament, and I would not recommend any church to adopt it.