We can't know the Ultimate Reality who is God
entirely, but He has made some revelation of Himself in Creation, in the record of holy Scripture, and in the Person of Jesus Christ.
Skepticism is a double-edged sword. In extreme degree, it becomes self-refuting. If nothing can be truly known, then the statement that nothing can be truly known is itself in doubt. Skepticism, then, can become quite irrational, if one is not careful to limit it.
Why aren't you skeptical of the notion of hell? If skepticism is generally your default setting, why not simply be skeptical of divine punishment?
The Bible says nothing about "magically believing." In fact, Paul the apostle spelled out a very rational basis for his trust in Christ:
2 Timothy 1:12
12 ,...for I know whom I have believed and am persuaded that He is able to keep what I have committed to Him until that Day.
For Paul, his trust in Christ was predicated upon knowledge that he was persuaded was true. There was no blind leap of faith as so many anti-theists today like to say is the essence of Christian belief. What is the knowledge, exactly, that persuaded Paul? There are three main realms of knowledge that led to his conversion to Christianity: The first is what is known as "natural theology." For a thorough investigation of this realm of knowledge go to:
www.reasonablefaith.org
Paul also had scriptural reasons to believe which he explains in his various letters to the Early Church. Third, Paul had a personal revelation, a direct experience of, God. Together, these things persuaded him to trust in Christ as his Saviour and Lord. There was, then, for Paul no "magically believing" in God.
Is it wish fulfillment and confirmation bias at work when a person interacts with their parents, or siblings, or spouse and is confident in their trust in these people? Obviously not. So, too, with the Christian believer. God is not merely a religious theory or a philosophical position to embrace and defend; He is a Person. He wants to interact with His children and He does. He convicts them of sin; He illuminates their understanding to His truth; He comforts them in trouble; He provides for their needs both spiritually and physically; He produces in them the "peaceable fruit of righteousness." When this is a person's experience of God, it is no more possible to doubt His existence than it is to doubt the existence of family, spouse, or friends.
God exists whether or not we experience that He does; a person's experience of God is not the ultimate arbiter of His existence. There are plenty of reasons quite apart from one's personal experience upon which to rest a faith in the God revealed in the Bible. Here are some websites that can give you a thorough explication of those reasons:
www.crossexamined.org
www.str.org
www.rzim.org
This assumes your position of agnosticism is somehow the best position to adopt. Obviously, those "elite philosophers" who are "hotly debating" natural theology on both sides disagree that your position is a good one. How, then, is your agnosticism superior to their affirmation or denial of the arguments for God from natural theology? Is the man who hears that the building he is in is on fire and responds with skeptical agnosticism to the claim wiser than the one who says it is on fire or denies outright that it is not? Is it a wise man who waits 'til the fire is licking at his toes before he abandons his agnosticism about its existence? No, a wise man would, given the potential danger, do the necessary work as quickly possible to ascertain one way or the other if the claim about the fire was true. It would be foolish of him to just throw up his hands and say, "Well, there is controversy about the reality of the claim that the building is on fire. I guess I'll just sit and wait until I see the fire before I'll make any sort of response." People who do this sort of thing end up crispy and dead. And their response is, practically-speaking, exactly the same as those who actively deny that the building is on fire.
For someone who claims agnosticism you are rather too sure about what is reliable evidence for God and what is not. The mere presence of controversy, however strong, does not necessarily mean that the truth is not and cannot be known. Imagine a man who jerks up from his table at a restaurant, clutching his throat and turning red in the face. Another man at a nearby table
says, "Oh, look! That fellow's meal was too hot. He's burnt his mouth and throat!" A woman glancing over leaps to her feet and shouts, "Goodness! He's choking! The man is choking!" She moves to help the fellow who's lurching about and waving his arms. "Just get him some ice or a glass of cold water. He'll be fine," says the man at the nearby table. There's some controversy over what is, in fact, wrong with the man who's staggering about. Should you sit back and do nothing? Would it be right to say to yourself, "These two are very certain about what they think is wrong. They've got the very same information but have come to very different but plausible conclusions. I suppose its impossible, then, to know what's actually wrong until the fellow tells us"? I hope not. Controversy does not mean the truth is not or cannot be known.
You have your supernatural occurrence in the resurrection of Christ. For more miraculous evidence read "Miracles: The Credibility of the New Testament Accounts," by Craig Keener. It's a two-volume set that offers very credible evidence, not just for biblical miracles, but for various miracles that have occurred since the writing of the New Testament.
It's been my experience that walking with God inevitably involves seeing His supernatural intervention in my affairs. I have seen Him do many incredible things for which a natural explanation just doesn't work. I recall my brother praying for a job and getting one but lacking the means to travel to and from the job. He couldn't walk or cycle the distance and public transit couldn't get him to his workplace. So, he prayed that God would also provide the means of transport to the job. He didn't tell anyone of his need or of his request. The next morning - the day of his first shift at the new job - a man arrived in a car. He walked up to the door of our house and when my brother answered the door, he dropped a pair of car keys into his hand and said, "God told me you needed a car. Here are the keys. Insurance is good to the end of the month. God bless." And then he got into another car that had pulled up and drove off. We were all quite stunned. My brother knew the man in only a second-hand sort of way but got in his new car and headed off to work.
When you say, "Only a supernatural sign will convince me God exists," you're putting yourself in the position of telling God what to do. He doesn't work that way. He won't jump through your hoops just because you demand that He do so. Look, He doesn't
need you to believe in Him. He's absolutely undiminished by your lack of faith. But you, on the other hand, very much need Him. Your eternal destiny hangs upon your coming into relationship with Him. Your life's purpose, it's meaning and fulfillment, is entirely contingent upon Him. So, you can fold your arms across your chest and try to order God to do a miracle for you, but I very much doubt He will. You must come to Him
His way, not yours. And if you don't, you're the only one who suffers.