Or do you mean anyone hallucinating Jesus during heat stroke is automatically an Apostle? (which is the secular description of what happened to Paul).
It's true that being a Christian does not require you to put your brain on a shelf. But it does require faith in the communication we have received from God. If you accept the Scriptures as God-breathed, that obligates you to consider as true those things proffered in Scripture for their truth value. Obviously, this does not mean you must accept every descriptive statement as normative. For example, that Judas went out and hanged himself is descriptive, but not normative, thankfully. But when the description of an event such as Paul's conversion in the road to Damascus is presented by the inspired writer as true, and particularly the interpretation of the event, then you must either accept those statements as conveying truth, or you must discredit the writer as not speaking under inspiration.
1. Which gets us to the first problem you have with Paul's account of his conversion and calling:
It isn't simply Paul who believes it and presents it as true. Acts was written by Luke, who states at the outset his purpose:
Luke 1:1-4 Forasmuch as many have taken in hand to set forth in order a declaration of those things which are most surely believed among us, (2) Even as they delivered them unto us, which from the beginning were eyewitnesses, and ministers of the word; (3) It seemed good to me also, having had perfect understanding of all things from the very first, to write unto thee in order, most excellent Theophilus, (4) That thou mightest know the certainty of those things, wherein thou hast been instructed.
So Doctor Luke most certainly believed Paul's Damascus account as Paul presented it. In fact, Luke presented it three times over (See Acts 9, 22, & 26), and not only did he not refute it, but deployed it to establish further truths, in particular the validity of Paul's ministry to the Gentiles, in which Luke, being a Gentile, would be most happy to concur as true.
2. The second major problem you have is this:
Jesus did rise from the dead. And if you accept this premise (as I am sure you do, BTW), you must hold any inscripturated record of a post-crucifixion appearance of Jesus as true, regardless of secular doubting. But if you succumb to the skeptics on this, you undermine the resurrection itself, because the skeptics deploy that same hallucination theory against not just Paul, but against Peter and all of the apostles, claiming none of them saw the real Jesus. No Christian can accept that premise:
1 Corinthians 15:14 And if Christ be not risen, then is our preaching vain, and your faith is also vain.
So again, if you accept that Christ is willing and able to make such appearances after His death and resurrection, you must at least accept the possibility that this is precisely what happened to Paul, without letting your medical background interfere by confusing a medical condition that can explain
some experiences of seeing bright lights, versus
other experiences involving a genuine divine appearance also associated with seeing bright lights.
3. The third major problem you have is this: The experience was what is known as an
objective vision, as opposed to
subjective. The principle criteria for the distinction is whether other individuals present experienced the phenomena when it occured. The post-resurrection appearances of the risen Jesus to the apostles were objective. They were experienced simultaneously by more than one person at a time. Paul accounted for his experience of seeing Christ as being in that same category, and therefore apostlically qualified:
1 Corinthians 15:3-10 For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures; (4) And that he was buried, and that he rose again the third day according to the scriptures: (5) And that he was seen of Cephas, then of the twelve: (6) After that, he was seen of above five hundred brethren at once; of whom the greater part remain unto this present, but some are fallen asleep. (7) After that, he was seen of James; then of all the apostles. (8) And last of all he was seen of me also, as of one born out of due time. (9) For I am the least of the apostles, that am not meet to be called an apostle, because I persecuted the church of God. (10) But by the grace of God I am what I am: and his grace which was bestowed upon me was not in vain; but I laboured more abundantly than they all: yet not I, but the grace of God which was with me.
Clearly in the above passage Paul is claiming the apostolic criteria of having seen Christ in the same objective manner as the other apostles, and so secures his claim to be an apostle, albeit unworthy in his own estimation.
The essence of an objective vision then it that it was not experienced alone, as was for example Peter's vision of the unclean animals made clean. Rather, as Paul recounts, and no one refutes, those who were with Paul had visual and auditory events that corresponded to Paul's. So even though Paul perceived them as a unique communication to him, it was an objective supernatural event, shared in some way by all present, by audible and visible insignia that everyone there experienced:
Acts 9:3-7 And as he journeyed, he came near Damascus: and suddenly there shined round about him a light from heaven: (4) And he fell to the earth, and heard a voice saying unto him, Saul, Saul, why persecutest thou me? (5) And he said, Who art thou, Lord? And the Lord said, I am Jesus whom thou persecutest: it is hard for thee to kick against the pricks. (6) And he trembling and astonished said, Lord, what wilt thou have me to do? And the Lord said unto him, Arise, and go into the city, and it shall be told thee what thou must do. (7) And the men which journeyed with him stood speechless, hearing a voice, but seeing no man.
And recounted again here:
Acts 22:6-9 And it came to pass, that, as I made my journey, and was come nigh unto Damascus about noon, suddenly there shone from heaven a great light round about me. (7) And I fell unto the ground, and heard a voice saying unto me, Saul, Saul, why persecutest thou me? (8) And I answered, Who art thou, Lord? And he said unto me, I am Jesus of Nazareth, whom thou persecutest. (9) And they that were with me saw indeed the light, and were afraid; but they heard not the voice of him that spake to me.
Both accounts show that the bystanders were aware of something extraordinary going on. The Greek in Acts 9 suggests they perceived some sort of sound, whereas the Greek in Acts 22 clarifies that what they couldn't hear was intelligible speech. This is similar to what happened when the Father spoke from heaven concerning Jesus. In that case some of the bystanders thought it was thunder, others thought it was an angel:
John 12:28-29 Father, glorify thy name. Then came there a voice from heaven, saying, I have both glorified it, and will glorify it again. (29) The people therefore, that stood by, and heard it, said that it thundered: others said, An angel spake to him.
The upshot of all this is that this was clearly an objective vision, i.e., there was not a medical condition at the base of it, but a miraculous intervention in the life of Saul that was witnessed by an audience hostile to the idea of a resurrected Jesus. The only way to refute this is to impugn Luke as well as Paul, and thus discredit the Fourth Gospel as well as all the Pauline epistles, as being recorded by unfaithful witnesses reporting falsehoods, thus eliminating in a single blow the majority of the New Testament.
4. The fourth problem you have is that the other apostles, purportedly under the guidance of the Holy Spirit, did not refute Paul's story, but rather accepted his ministry (Acts 15), which we know from Galatians (and many other places) he conducted openly under color of apostleship. This appears to be an acceptance by the apostles of Paul's apostolic mission to the Gentiles.
So, by impugning Paul's apostolic credentials as being nothing more than a "beneficial" medical condition, you are in effect saying the apostles in Jerusalem, including Peter, got it wrong, that they were not being led by the Holy Spirit, or worse, that the apostles and the Holy Spirit were complicit (and I speak as a man, God forbid this should be the case) in allowing a deluded man to think he was an apostle, when in fact he wasn't, to think he encountered Jesus, along with audible and visible manifestation for his associates, when in fact it was nothing more than a mysterious simultaneous attack of heat stroke for the entire group. Can you hear the plausibility cracking?
In other words, he preached locally but wasn't an apostle.(Ac.4:36-37)
As for the notion that Paul's ministry was strictly local and therefore somehow not apostolic, that is defective for at least two reasons:
1. First, even if we granted the erroneous assumption of being merely "local," what criterion of apostleship does that violate? None. Being sent to do a mission does not automatically infer some minimum of distance, as in, if he doesn't get X number of "frequent traveler" miles under his belt, he's therefore not an apostle? Huh? Sorry, but that is laughable. And without basis in Scripture.
2. Second. the idea that Paul's ministry was local is ludicrous. He had three missionary journeys that took him farther and to more places than any of the other apostles, at least as recorded in Scripture. See the following maps with supporting Scripture:
http://www.ccel.org/bible/phillips/CN092MAPS1.htm. So even if miles traveled were a real criteria of apostleship, none of the other apostles come anywhere close to being as much an apostle as Paul. But I speak as a man. The criterion is ridiculous.
When Barnabas saw the Gentiles being swept into the fellowship of the Church he was glad; but he recognized that someone must be put in charge of this work. That someone must be a man with a double background...
So essentially it was Barnabas who "appointed" Paul to preach to the gentiles. I could go on, but I advise you read it for yourself.
Again, by way of review, there are multiple witnesses to the fact that Paul was called by Jesus directly to be an apostle. The only way to challenge that is to discredit the bulk of New Testament Scripture. The reason the hallucination hypothesis exists at all is because it is precisely the goal of the skeptics (which is not the same thing as secular) to discredit Scripture, only they are generally more consistent, in that they apply the hallucination theory to all the post-crucifixion appearances of Christ, and thus discredit even more of the New Testament record than you do.
But as a Christian I reject the premise of the skeptic, and proclaim with Paul:
1 Corinthians 15:20 But now is Christ risen from the dead, and become the firstfruits of them that slept.
And entailed in that resurrection are a thousand other impossible good things God has done and will do for His people, whether making Paul an apostle on His own authority, or making followers of Jesus out of skeptics, which I once was. Praise God for His amazing grace.
Peace,
SR