Philosophy is a science based on logical Deduction, Induction, Abductive and Analogical Reasoning. Unlike pop science, speculations and invention have no place in philosophy. In philosophy it has to make sense. "Logical deduction is the process of reasoning from one or more statements (premises) to reach a logically certain conclusion. If all premises are true, the terms are clear, and the rules of deductive logic are followed, then the conclusion reached is necessarily true."
Philosophical reasoning can be used to prove that God exists. For example, we can see that our universe is in constant motion. Yet we also know that something must have started all that activity. No inanimate object can simply start moving on its own. Something outside of a thing must interact with it in order to affect it, for example to give it a push. Only a living thing can move on its own, using its free will.
From that we can deduct the following: The motion in the universe was injected into it from something outside the universe. Furthermore, the ultimate source of the outside force must be a living thing, with free will. This is what in philosophy is referred to as a Prime Mover. There has to be a beginning to the chain reaction of motion, and it must have done it on its own. We know this has happened because today we see motion.
"An argument is 'valid' if it is impossible for its premises to be true while its conclusion is false." Is it possible to have universal motion without a source of that motion? No. The Earth turns as result of a myriad of gravitational, charge and physical interactions that might be tracked backwards to a single source of motion. Yet an object remains at rest unless something from outside that object gives it motion. What was that first source of motion?
If the universe existed forever then it would have gradually run itself down long ago, through a natural process of friction and collision. It is still moving, therefore it had a beginning. What was that beginning like? Pop scientists make their money speculating on the beginning of the universe, but philosophy demands logical proof. Neither science can provide physical evidence and so the pop scientists are quite happy to postulate all day long, no reasoning required. Philosophers need much more rigor than that.
What can we know about the beginning of the universe? Before it existed, it did not exist. So what caused it to transition from non-existence to existence? The mechanics of that transition are not nearly as important as the cause. As we know, universes don't just pop into existence on their own. They need a push, from outside. That's what we call the Prime Mover, or God.
Now it's true that we can't use Philosophic reasoning to prove the nature of God, or His activities with humanity. However, we can easily prove He exists. Once we know He exists then it's up to us to find out what he wants from us. Pascal says that there are three kinds of people: those who have sought God and found him, those who are seeking and have not yet found, and those who neither seek nor find. The first are reasonable and happy, the second are reasonable and unhappy, the third are both unreasonable and unhappy. Which are you?
http://www.peterkreeft.com/topics-more/20_arguments-gods-existence.htm
