Well, since I'm done with my rant above, perhaps you would find it helpful to get a sense of where the ideas you ran into come from?
Once upon a time, when the Church was very young, and most of the population of society was decidedly non-Christian, the Church had many people coming to investigate what it was teaching. They came from all sorts of backgrounds, but mostly one form of paganism or another. The culture was a rich milieu of all sorts of religious ideas, sometimes so syncretic that it was hard to tell who really believed what. People who called themselves Christians were often more heterodox than orthodox excepting Gnosticism and denying the very foundations of the Christian faith that Jesus was either the incarnation of God or that he could have died on a cross.
In that sort of environment, the Church began the practice of holding a catechism (teaching) as a part of their gathering for worship. The catechism would come first followed by the Eucharist (with the sharing in the body of Christ). However, what they did was to dismiss all those who had not yet completed the catechism before continuing with the service. These folks who either were simply still just searching, did not understand the faith, or had otherwise not yet made a decision that they really believed the stuff that the church taught as orthodox beliefs would be excused from participating in the rest of the service that was then seen as the sharing in the body of Christ (the communion) by the Body of Christ (the fellowship) in which the Church gave thanks (eucharistia) for Christ’s offering of his body as a sacrifice on the cross.
Now, the primary way that the church gave witness to Jesus’ sacrificial death was not just a memorial service (for the Eucharist was far more than just a memorial), but was in the self-identification with that death in the act of baptism. For baptism was seen as an act of dying to self, being buried (in the waters of baptism) and then being raised to new life. In other words, baptism wasn’t about the washing away of sins (Christ’s blood in the Eucharist does this), but bearing witness to the celebration of our resurrection and new life in Christ. So, when the catechumenate was ready to bear witness to this being something they trusted to be true for themselves in Christ, they would be baptized and then move from taking part only in the catechism part of the service to also receiving the Eucharist with all others.
Of course, today, other than the reading of a short bit of scripture and a sermon, most churches do their ministries of teaching completely apart from the worship service in dedicated Bible study classes, small groups, and Sunday school; and catechism is a hoop we make children jump through called confirmation. As a result, we have children who have been baptized who participate in receiving communion, but slip away from the church never confirming their faith (or often right after doing so). And we also have adults who come to faith completely outside of the church’s programs designed for education, begin to participate in the life of the church, and then only after significant growth in faith and multiple public proclamations of faith seek to get baptized.
As you’ve learned some congregations still maintain the idea that the receiving of communion still needs to be restricted as it once was, while in the UMC we do not. And another reason for that is because we also know that as early as the above pattern developed (and it was early, probably the 3rd or 4th century), it was NOT the pattern of the New Testament church which shared their communion meal as a true fellowship meal, a place for any and all to gather and share and learn about faith in Jesus. It was for any and everyone, even those who had never even heard of God, let alone believed and had been baptized. Because it wasn’t a ritual meal; it was supper. And it was in the sharing of that meal (having more in common with the way we serve pot-lucks than the way we serve Holy Communion), in the breaking of bread, that people remembered what Jesus had done, his sacrificial death and resurrection, and they sat and talked about their faith, nurturing it in guests who had none whatsoever. But, if during the meal, a guest might come to also confess faith in Christ; then, after having already participated in the Lord’s Supper they would be asked to affirm their faith in a ritual of baptism.
So, there you have two different patterns in the life of the Church. Both appearing very early. As a ritual, the pattern has been baptism before communion. As historical events, the pattern has been sharing in the communion meal before baptism. Then add, that the NT Church (at least in the opinion of this UM pastor) also practiced infant baptism, which would become normative later in time, and we have all sorts of different ways the Church has ordered its sacred acts of worship.
BTW, an interesting bit of trivia: Do you know where the term “mass,” the name that Catholics use for their celebration of worship, comes from? It comes from the dismissal of the catechumenates. They were dismissed in mass while the rest of the congregation (generally the smaller part) continued to worship through the celebration of the Eucharist. Today a Catholic mass is for those who are a part of the Church and can receive the Eucharist, but originally it referred who were not and could not.
