In the story of the Ethiopian eunuch we have a model for Evangelization and a caution away from the two extremes. One the one end is the Catholic tenedency to over systematize. In response to his question what is to keep me from being baptized, many of our people would have responded, "You haven't spent a full year in the RCIA." The other extreme would be the idea that he could just sit by himself read the Bible and profess faith in Jesus. Both miss the mark.
To those who would say that a person can read the Bible on there own I would respond with the dialogue with Philip.
Do you understand what you are reading?” He replied, “How can I, unless someone instructs me?
It is not that this man is ignorant. He is educated and powerful. He is probably versed in multiple languages. The word used here means literally to lead or to guide. None of us can be our own spiritual guide. Left to our own devices we can all too easily transform the faith to us, rather than allow the faith to transform us.
Philip begins where the man is. He begins with the passage and the provides him not with a complete instruction in the faith but with a sufficient instruction. Clearly it entailed much more than is recorded in Acts because the man knew enough to know the nature of baptism with water.
In our Catholic understanding of the faith. Baptism is the gate or door through which we enter the Church. It is merely the beginning. Most of our formation in the faith will take place as we live it. For the child under the age of 7, the parents and godparents should understand the obligations that having their child baptized entails. For the person over the age of reason, they should understand, according to their ability, the commitment they are making in asking to be baptized.
The man puts the question to Philip. He does not demand baptism as if it is something to which he has a right. But he requests it. It is left to Philip to make the pastoral judgment as to whether he thinks the man is suitably prepared. As a pastor, the shepherd of a flock it is is often a difficult process of discernment. When a person is sufficiently prepared they are to be baptized.
Intrestingly the law of the Catholic Church never allows a pastor to deny baptism. It says that if the hope that a child will be raised in the faith is prorus (completely) lacking, the baptism can be delayed until there is some foundation for hope. The simple fact that the child cannot be his own teacher in the faith.
This story from the Acts of the Aspostles remains to this day our model for preparation for baptism.