I don't have any problem whatsoever with allowing credo people to join my church. When they vow to submit to the governance and discipline of the church, that vow should not be interpreted as saying that if they refuse to become paedo, they will be expelled from the church. On this thread, I have seen a too-narrow definition of church discipline. Church discipline is not only negative. Bruce was getting at this a bit in terms of willingness to be taught. That is the key. The discipline involved with a credo brother or sister in Christ would involve long, careful, biblical exposition and teaching that could take place over years. To a paedo-baptist, the position of credo baptism should not be nearly the same thing as living in sin. Discipline is teaching. If after several years of patient instruction (and if often takes that long!), the credo is still unconvinced, then I would encourage them to seek another church, but I would never expel them. That is exercising church discipline, but it doesn't have to be on the road to excommunication. We need to broaden our definition of discipline. Of course, as has been mentioned, there are several Reformed churches that require confessional adherence in order to be a member. The PCA only requires that of office-bearers, and not of its members.
For the most part I would agree, but the confession calls neglecting baptism is a great sin. Would you withhold membership from an adult professing believer if they did not submit to baptism? If so, what is so different between that and withholding baptism from their children? Would you allow membership and then go through a long process of instruction in order to bring them to the point of understanding baptism is required?
What I am not saying is that those that are credo cannot be admitted to membership, and that the process of instruction should not be gentle, persistent, and long in duration. But it would seem to me that not eventually going to more and more severe as it becomes evident that the parents are not just not convinced, but are unwilling to submit to authority over them in their indecision.
Ultimately, the position of the WCF is that those who neglect baptism are in great sin. For a believer, this negligence would be their own baptism, and it is unlikely the person so neglecting baptism would be allowed to become a member. For parents of children, the neglecting of baptism would be for their children's baptism (as the parents would already be baptized if they were members) and it would still be, in the words of the confession, great sin.
Should any member of the church be living in a state of great sin and be allowed to the Lord's Supper? This is continuous, and in a paedo church, I think ought to be dealt with as any member in any flagrant public sin. Certainly it requires gentle, correction, teaching and guidance, but when does the church exercise the marks of the true church and exercise Biblical discipline in order to bring the erring sheep into the fold?
If great sin is not worthy of correction, then what do we call sins that are worthy of correction.
You raise good points here, Brian. I agree that neglecting baptism is a great sin, even infant baptism. But I do not believe that all sins should be dealt with in the same way. I guess what I look for is whether or not a person is willing to be taught, as Bruce mentioned. If that teachable spirit is there, then we can go a long ways. If the person came in under false pretences, saying that they are teachable, when in fact they're not, then we have a serious problem. And we should discipline for wrong opinions just as surely as for wrong practice. There should be no divorce between the two. I'm hearing agreement on this point in your post. But to me, the issue comes down to this: how do we define the visible church? If a person professes faith in Jesus Christ, is that not the most important requirement to belong to the visible church? The tightness of the circle for membership concerns me here. Would we be saying, for instance, that a credo cannot be part of the visible church, if we make paedo-baptism a membership requirement? Should the entrance requirements for a church be the same as the requirements of belonging to the visible church anywhere, at least in terms of correct doctrine? I think this issue deserves more thought and care.