I have to say that the question is a lot like asking “why do I have to go to my state of residence to get a drivers’ license, instead of my state of choice, just because I happen to live there?” Not to be trite about it, but it really is the same principle.
More directly to your question: Because a parish is a territory. It’s the very definition of the word. Yes, some parishes can be personal (and that’s completely legitimate) but personal parishes* are not the norm.
Whether or not some people like this (and no, that’s not directed at you personally, but a general statement), the fact is that the Catholic Church has decided that parishes are territories.
A pastor has jurisdiction within his own parish. Likewise, a bishop as pastor of his diocese. That means that he has both the ability and the responsibility for the care of souls within that territory.
Especially when it comes to administering Sacraments that require some kind of jurisdiction, parish territories are relevant in the extreme. When it comes to marriage, the very
validity of the marriage depends on this jurisdiction. Even though it’s not the topic of the thread, it does form part of the answer to the question you’re asking me.
The Churches laws and norms for administering RCIA are quite complex. Bishops have different responses to exactly what they allow parish pastors to do. Most Catholics don’t realize that baptizing an adult is reserved to the bishop (canon 863) although he can delegate this to pastors. That’s why this is so important to the OP’s question. No one here can know whether or not the OP’s bishop only gives permission to pastors to baptize adults who actually have a residence in the parish.
The other relevant point is that pastors have a responsibility to administer the Sacraments to their own parishioners (those who reside within the parish). A pastor is well within his rights to have a policy of not admitting potential RCIA candidates unless they live within the parish. This happens very often in places where people try to pick a church based on something like architecture or aesthetics (although that’s more common for weddings).
My point is that a Catholic, or potential Catholic, needs to be aware when someone crosses parish boundaries there is a possibility things might not work as planned and there’s a possibility for misunderstandings or other problems in the future. Telling someone “it doesn’t matter” or “it makes no difference” is objectively untrue. Exceptions can be made, and often are made; however exceptions do not mean that parish boundaries do not exist or do not matter (which is what many posters on CAF erroneously claim).
Simply put, saying to someone “talk to the pastor” is the correct answer (and not just because I wrote that). It’s objectively the correct answer. On the other hand, telling someone “it doesn’t matter” is objectively the wrong answer.
For the OP’s situation, it’s necessary to begin by talking to one or the other pastor; and I would suggest by starting with the pastor where the OP would like to enroll in RCIA. No one here can say whether or not he can baptize an adult who does not live within his parish, and no one here can say whether or not he will be willing. Especially because the OP intends
specifically not to continue attending that same parish after completing RCIA, only that pastor can answer the OPs question—not someone on the internet.
It’s even worse when people post anecdotal responses like “I did it this way…” or “my pastor says he doesn’t care…” Those kinds of responses aren’t helpful to the OP when this kind of question is asked.
- Just so that (some) readers here understand the vocabulary: a parish is said to be “personal” when the membership is determined by who is eligible to join (by persons) rather than territory. I recall in the seminary, when we first heard about “personal parishes” we thought that meant someone’s private parish—hence my explanation.
