My answers will not improve the ones already provided, only add a little emphasis here or there.
Granting your pastor's outsider perspective, he may not see in P&R folk the same urgency (as he is used to promoting) for bringing a child to a "give your heart to Jesus" moment. "Decisional regeneration" is sort of the flip-side of "presumptive regeneration," and doubtless there are defenders of either one exactly, as well as those who don't think much how to characterize their own general outlook while criticizing the other extreme. Suppose you have a Calvinistic Baptist pastor, who would be scandalized by the suggestion that he teaches regeneration-by-decision; yet to an outsider, it may appear he operates on that very principle.
Now, whereas our Baptist brothers tend to think of disciples as those who have clearly and unequivocally given their hearts to Jesus, the Presbyterian thinks of disciples as visible members of the church. Children of professing believers are disciples, i.e. they are being taught THE FAITH which they are expected (in due time) to express on the basis of an internal reality. From infancy, within the bounds of the covenant their minds and hearts ought to be weekly, even daily pressed with the facts pertaining to the Person of Christ in whom they are to put all their trust. They are "learning Christ," Col.1:7, Eph.4:20, which is the definition of a disciple. What Presbyterians shouldn't say is, "My child is no different from a mature disciple," or, "I know how far the Spirit has gone in any secret work upon the soul of my child."
The first time I meet you, if we find we are both citizens of the same place I take you at your word, and also act toward you as if you harbor no secret treason in your heart to our common kingdom. A kind regard for you makes no room for unfounded suspicions. In that scenario, I could have a much deeper acquaintance with our kingdom's constitution than you, and know more fine points of its operations having encountered more of them. At the same time, you could have taken a soldier's or a policeman's oath of defense of the society, a step I had never done. For all that, one of us could prove false in the end. But the day we met, we each recognized the other as fellow citizen, and your children were no less in my eyes.
Do I know your children will not turn traitors? No, now I'm not going to treat them as either aliens or as mature citizens, but as minors with the privileges of citizenry. They may not drive, nor vote, nor do any number of things only suited for one who has grown up and not been charged with a felony. I expect the mature citizens around them will both keep their eye on them, and train them up in the good ways of the society, all without despising them or assuming more of them than is proper; and hope reasonably for the best. This is something different from expecting every would-be citizen to formally choose his identity for himself at some point, so that every citizen is acknowledged a former alien and naturalized oath-taker.
In the kingdom of God, administered through the church, the P&R perspective understands discipleship starts somewhere and never ends. We understand the context of rearing covenant-children is the kingdom. Our focus is not on becoming or having already become a disciple, but on BEING a disciple. We should understand that we feed on the gospel, on Christ in the gospel, always. The gospel is not merely the door of the kingdom, but its sustenance. We are daily being saved, just as much as we were saved, are saved, and will be saved. What's true for me, is also true for my child. We are disciples. We are visible Christians.
No one knows my heart but me, and God. They hear me say I'm a Christian, I make some effort at living as a Christian which is seen by others. My child is entitled, I think, to say the same even if he hasn't passed through "Ellis Island" or every other checkpoint on the list of things to one must do in order to be saved. He acts for the most part in conformity with his training. But a good little boy or girl is not to be counted a Christian because he or she is compliant and keeps the law, nor should we so judge the adults in the room.
The law doesn't measure the quality or quantity of discipleship or maturity. God's moral law must be taught, must be known. It is the standard, against which we may constantly judge ourselves--and a fair assessment always comes up short, finding us wanting. To come a little short or a lot short is (in the most vital sense) irrelevant. Our failure should leave us sorrowful, no matter how great or small; and then we should look unto Jesus, who is our sinless law Keeper. That's the message we should be telling our fellow, grown up professors; and also our children. May that be the only message about personal righteousness they ever hear from us and from the church. "Believe on the Lord Jesus Christ and you will be saved."
Communion is for professors. Baptism is for those who 1) choose public identification with Christianity for the first time personally, and 2) for those who have had that choice set for them as their starting point; in either case it is something that happens to a person by the power of another. In this, baptism is the sacrament associated with (not identified as or instrumental to) justification. Communion is the sacrament associated with sanctification. It is for someone who is more mature, "of age," able to examine himself to know if he has good cause to approach the table of the Lord or refrain from it. Readiness for communion--a judgment of the heart--is comparable to the OT Israelite's external assessment (that still demanded internal examination) of ceremonial cleanliness. An unclean Israelite who dared to partake of the feasts and altar (conjoined things) was to be cut off from his people. Self-examination has always been a part of covenant meals; adjudicated cleanliness is never waiverable.
What is a "conversion experience?" Do you have to remember the day of your birth to know it happened, and was real? Or does your knowing you are now alive suffice for proof that birth surely did take place? You did pass through a birth canal, even if metaphorically due to a caesarean delivery. You went from one state to another. And to be living in newness of life, you must have been born again, even if the moment of time is now shrouded in mist. You passed from the state of death to the state of life, Jn.5:24, 1Jn.3:14, not because the moment is memorable, but because today you are a hearer of the Word, and because you love your brother.
The apostle in his Gospel and his letter encourages the Christian with a brief acknowledgement of the transient validity of current evidence, something you are right now experiencing. Not listening to Christ? Not loving your brother? You know what you are doing right now, so if not there's some reason for you to be concerned. If you are, there's real hope. That's the behavior of a disciple. If you have a "conversion experience," great, nothing wrong with one of those. But experiences vary, especially as to their memorable quality. Our spiritual reality is not memory based, but fact based. I would encourage my children to rest in the latter, not the former.
