One does not have to wonder whether or not he is baptized. That is what I mean by objective. Visibly, the person is made a member of the Kingdom of God. Yes, he may rebel and shrink back but there is no presumption that no membership or responsibility to continue belonged to the individual.Rich, what's the definition of "objective"? What about in the case of excommunication from the church? Is it not the case that that person has been removed from the visible kingdom? If I'm not wrong, Presbyterians believe that it is not one's baptism per se that marks him out as belonging to the covenant community, but his continued membership in the local church and the common confession of faith. That covenant status, by implication, is only objective at the time that the conditions are being met. However, it can be rendered undone through unfaithfulness within one's lifetime, as was the case with circumcision.
It is objective in contra-distinction from a subjective apprehension of Baptist theology: "Did I have real faith when I was baptized? Golly, I don't know. When I was baptized as an adult I held to an Arminian soteriology. Maybe I was never really baptized." or even "I know I believed the right things when I was baptized but this heinous sin I've committed leads me to doubt whether or not I had real faith when I was baptized. Maybe I was never really baptized." Ultimately, the tenor on the reality of baptism in Baptist CT rests on the subjective experience of the individual.
No, not every time that Baptism is spoken of it necessarily speaks of union with Christ. The Romans 6 sense of the term certainly does to the point where the baptism being spoken of is a spiritual identification with Christ in His death and resurrection. Paul there speaks about baptism in a way distinct from the actual administration of physical baptism. In other parts, baptism is spoken of in its external administration - men rejoice at the news (and by all external indicators believe and repent) and they are baptized. Yet, it is abundantly clear as well from other portions that even men that Paul labored in the ministry with fell away.I would also ask of the scriptures, whether it sees baptism in this 'ideal' sense. In most cases that I can think of, the mention of baptism is coupled inseparably from their status as united with Christ and saved. One can cite Simon the sorcerer who was baptized but doubtfully converted, (although he might have been, we don't know). One thing is for certain, he was immature and was disciplined. If unconverted, Scripture would say of Simon, "they went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us." (1 Jn 2:19). This sounds a lot like what you think Baptists would say. But interestingly, in Simon's case, it is still affirmed by Luke that "Simon himself believed and was baptized" (Ac 8:13). Thus his baptism was still justifiable because he believed.
Clearly, then, there is a connection between the sign of baptism and the thing signified but it cannot be said that because a person receives the sign that he necessarily possesses the reality. You can find in Scott's post that connection. Physical baptism is sacramentally related to spiritual baptism in that God has instituted it and promises that He attends to the Promises announced in it. The Holy Spirit gives the graces it signifies to the elect and this is why the timing of baptism and its reality does not depend upon the subjective experience of the recipient. Again, it is God's speech and not ours.
In Simon's case we cannot fully conclude that simply because the text states that he believed that it is speaking of true faith and repentance. There are several examples of "judgments of charity" in the Scriptures where people are assumed to be Christians on the basis of their profession. It's the way the Church must operate. One does not have to infer that Luke was given special revelation concerning the true nature of Simon's faith. Imagine what the Church would be like if we all walked around saying to one another: "You say you believe the Gospel but I have no way of knowing that infallibly so I won't ever say 'Dennis believes the Gospel'".
Again, that depends. If his initial conversion is not seen as genuine (or the person himself comes to that conclusion) then baptism is not seen as having occured and, in Baptist thinking, no "re-baptism" occurred because the person was never baptized.I'm not sure how baptists treat a backslider or one who is excommunicated, who comes back , but I imagine it's similar to how a Presbyterian church would treat him. A second baptism is not necessary.