I've posted on this before, but it is interesting to see how my Baptist brothers have continued efforts at re-tribalization in the aftermath of the SBC a few weeks ago. Part of this is the result of the failure of a resolution proposed by Tom Ascol (pastor, Grace Baptist Church, Cape Coral, FL), which essentially demanded that SBC churches remove non-active members from their rolls and bring integrity to their claims for a "regenerate church membership." This resolution never made it to the floor, having been rejected by the Resolutions Committee and then not receiving the necessary 2/3 vote on the floor to reconsider it.
As a result, some of my brothers have been blogging about the need for a regenerate church membership and restrict membership to those who have been "scripturally" baptized (i.e. "believer's baptism"). While I affirm that these are historically part of what it means to be Baptist (as Al Mohler rightly points out), these two issues were also a major reasons why I could no longer remain Baptist. Simply put, in my mind, Baptist ecclesiology is inherently sectarian (and that is not a good thing). Let me say also that, thankfully, most Baptists' hearts trump their doctrinal claims on this matter and they end up loving Presbyterians anyway.
For me, it was the ideal of regenerate church membership that broke down first. Being someone who specialized academically in American religious history and who has done work on Jonathan Edwards, I came to be convinced that it was impossible to peer into someone's heart to determine whether or not he was regenerate. All one could do was judge the "fruit" that accompanied his profession; and sometimes the professions are illegitimate. And if you have illegitimate professions of faith, that means you have hypocrites accounted as true members of the visible church. And if that is the case, then that means the visible church is a mixed body of believers and unbelievers (posing as believers). The end result was this: the Baptist claim for regenerate church membership was an attempt to make the visible church into the church that God alone can see (which is "regenerate" because it consists of the elect through time and space). Since this is clearly impossible (as the 1689 London Baptist Confession itself confessed), it is not an ideal that is biblically demanded for the local, visible church.
Once that principle fell, I was freed to think about the visible church in the way that I see it on Sunday morning (as well as the way I see it in the Bible): as professing believers and their children, who are set apart, holy, for God's purposes in their lives (1 Cor. 7:14). And since these children are admitted as part of God's visible people, they should receive the sign of entrance into that people, which in the OT was circumcision (Gen. 17) but in the NT is baptism (Acts 2:38, 39; Col. 2:11). God's purpose has always been for entire households to be identified with God's visible people (Gen. 17; Acts 16). The upshot here is that these two understandings--the visible church consists of believing households and the sign of admittance into the visible church should be applied to the entire household as a result of the household head's profession--made Baptist ecclesiology impossible for me. And so, I joined the Presbyterian church.
Now the reason Baptist ecclesiology is essentially sectarian is this: Baptists claim that they alone have genuine baptism because they alone "scripturally" baptize; hence, they alone represent the "true" (i.e. biblical) church. They claim this even though for at least 1850 years, there have been those who disagree with their claims abut baptism. They claim this even though most of the theological giants of the Christian tradition were baptized as infants (by sprinkling or pouring, but that is another matter). And so, with this claim (even though they don't want to do so), they essentially unchurch the majority of the Christian tradition. That represents the basic sectarian position--and as someone who studies the Christian tradition, this seemed to me to be an untenable claim.
Thankfully, as I've already said, most Baptists don't act on their basic principles and live out this sectarian position (although I am always concerned to see my friends defending Landmarkism, which would lead to real sectarianism). But the big reason why I became Presbyterian was that the doctrine of the church seemed to open the doors of the church as wide as Christ himself does--all those who believe in Jesus Christ for salvation and who are baptized in line with Matthew 28:19-20 (which only requires a Trinitarian baptism) are my brothers and sisters in Christ. This affirms the larger body of Christ (John 17:21) and seems to me to represent the best (and most biblical) position. It also allows me to affirm my Baptist friends as brothers in Christ (and even invite them into my pulpit), even if they might look a little sideways at me.