Many people say they would believe in God if they had airtight proof of some kind that he exists.
In his book, The Reason for God, Timothy Keller suggests that although you cannot “prove” the existence of God, there are “clues” in the universe that make very compelling arguments for it.   One clue is the fact that anything exists at all.  Almost all scientists agree that there was a point in time when our universe came into being.  How does everything come from nothing? Scientist Francis Collins writes: “I can't imagine how nature, in this case the universe, could have created itself.  And the very fact that the universe had a beginning implies that someone was able to begin it.  And it seems to me that had to be outside of nature.” Â
Another clue is what many refer to as the “Fine-Tuning Argument”, which is the view that the universe was prepared for human beings.  “When you look from the perspective of a scientist at the universe,” says Collins, “it looks as if it knew we were coming.”  He points to things like the gravitational constant, and the various constants of the strong and weak nuclear force and such, that have to be very precise if the universe were to exist and sustain life.  The probability that these constants all happened by chance is extremely unlikely.  “The odds against a universe like ours emerging out of something like the Big Bang are enormous,” concludes physicist Stephen Hawking.  “I think there are clearly religious implications.”
Then there are the “laws” of nature. For instance, we know with certainty that water will boil tomorrow under the identical conditions of today. However, our certainty is not based on “proof”, obviously (since it hasn't yet happened), but on faith.  We are assuming that there is an order to the universe.  However, there really is no scientific explanation for that.
Unsatisfied longings stirred by things like beauty, art and music – for love, meaning, justice, truth, happiness and eternal life, are also powerful clues for God.  Dr. Keller points out that innate desires correspond to real objects that satisfy them, such as sexual desire (corresponding to sex), physical appetite (corresponding to food), tiredness (corresponding to sleep), and relational desires (corresponding to friendship).  But what about these deeper longings?  Aren't they also innate?  We have these longings that no amount or quality of food, friendship, sex, success or “high” can satisfy. “We want something that nothing in this world can fulfill,” writes Keller. “Isn't that at least a clue that this 'something' that we want (ie. A loving, righteous, personal God; heaven) exists?”
Certainly,  none of these clues alone prove the existence of God. However, in the light of these (and many other) clues it is unreasonable to conclude that God doesn't exist. If there is a God the cause of the Big Bang, the fine-tuning of the universe, and the laws of nature make perfect sense.  Much more so than if God did not exist.  In fact, if God does exist, one would expect the universe to be the way it is. Moreover, if God were personal we would expect to have  longings that this world cannot satisfy.
“So what?”  If the clues mean there is a personal God who made everything, then there must be a reason as to why he did.  No doubt the key to our purpose in life is found in that reason, and it is connected to God himself.  Jesus Christ claims to know the reason, and it is better than you and I could ever hope or imagine.  Isn't it worth some investigation?  I would suggest The Reason for God as a good starting point.
