Bunyan's view was that differences over baptism were no bar to communion/church membership. (I think this was discussed at length in either this thread or the other one Bill started on the LBCF and immersion.) As I understand it, it is similar to what the Evangelical Free churches and some Bible churches practice. I know that at least some in this category go further than Bill and will admit those who were sprinkled prior to a profession of faith (e.g. as infants) as well.
As Bill notes, his scenario in which a man or woman was baptized by a mode other than immersion is pretty rare. Even in those cases, most who wish to unite with a Baptist church ("Reformed" or not) will almost always want to be immersed since that is what is taught there. Joining a church, especially one that majors on doctrinal teaching and preaching, would seem to necessarily entail some identification with the church's teaching and practice. Joining a church like Bill's is something to which more thought is typically given compared to joining the big steeple church on the corner on Main Street or the multi-campus megachurch in the suburbs.
Nevertheless, I do believe Rich is correct in noting that Bill's stance as articulated raises some implications as to what Bill thinks the mode really is. My guess is that Bill might say something like "
We practice immersion here because we believe it to be the biblical mode. Baptism by sprinkling or pouring is irregular but not invalid, thus we will not divide over the issue so long as the baptism was subsequent to conversion." This would be similar to how the Reformed throughout history have tended explain their acceptance of the validity of Roman Catholic baptism. As I recall it, their basic argument is that Roman Catholic baptism is irregular but not invalid and that like circumcision, baptism is not repeatable. In other words, it is definitely not recommended, but nevertheless the validity of the sacrament or ordinance is upheld because it is still trinitarian, etc. (Not all Reformed churches accept RC baptism, but the majority have historically, with the notable exception of the Southern Presbyterians in the USA.)
In my experience (which may be colored by my living in the Deep South) examples of those who are in effect "credo baptized" by sprinkling as adults or as older children in paedobaptist churches are relatively rare, as most in those churches are typically sprinkled as infants. Those coming in from the outside typically already have some church background and will have already been baptized (in some form acceptable to paedos) at some point previously. (What amounts to a late stage paedobaptism is all too frequent in many baptistic churches as well, where children as young as 5 or under are baptized.)
However, the numbers of those who come of age who have little or no church background (using church very loosely here) figures to become more common in the future as our culture identifies less and less with Christianity, even in the Bible Belt. No doubt it is already more common in other areas than my native Deep South. Thus, the cases in which a believer is baptized by sprinkling or pouring subsequent to a profession of faith may increase in the future.
What have you seen that "strongly supports paedobaptism?" You can send a PM or start another thread if you like since that is somewhat off topic in this thread.
A question for Bill: Would you accept a credo-sprinkling (or pouring) from basically any non-Catholic and non-cultic group? Would this include mainline Protestants? Would you limit it to evangelical churches? Or would you limit it to confessional Reformed churches only?
It would seem to me that if one who holds to some latitude on mode when accepting members were to accept an immersion from any of the above groups, consistency would demand that one must accept a credo sprinkling or pouring from them as well. The reason I ask the question is that I would imagine that some in the "Reformed Baptist" camp might more readily accept a man who had been sprinkled after having come to faith in the OPC or PCA as opposed to the United Methodist Church or the United Church of Christ.