Ok, in short I will try to give my reasons for thinking there is a God. Sorry if this turns into a long post, and I wont be able to explain it all fully.
If you justify the existance of a deity, then I think it's worthy of a long post.
However, we run the risk of derailing the thread. This looks like it could be an interesting discussion, so perhaps we should take it to PMs?
Starting with philosophy, the kalam cosmological argument which says that anything that has a begining must have a cause. The universe had a begining(this can be found using the big bang theory or other philosophical arguments that arenot worthy typing), therefore the universe had a cause.
Suffice to say, the Kalam argument is the poorer of the cosmological family. It's initial premise is based on a mathematical fallacy, and so it's conclusions do not logically follow (though they may still just so happen to true).
The Big Bang theory does not say the universe
began 13.5 billion years ago. Rather, it posits that the known spacetime continuum and all the matter and energy therein was confined to the tinyest of volumes. For all the theory cares, there could have been a salamander two years before it, whose poop became the 'cosmic egg' (to borrow from Hindu cosmology).
Furthermore, quantum mechanics is grounded in uncaused events and spontenatity; to use the Kalam argument (or any other First Cause argument) requires the rejection of QM. As a theoretical physicist, I do not recommend this

.
There may be theorys on what made the big bang, but none I know of that are anything but theories with no evidence.
Without being offensive, this statement highlights your scientific ignorance: a theory
by definition has evidence. Quite how an unevidence theory can exist is beyond me.
Also the teleological argument. This states that there is far too much in the universe that looks designed for it all to be down to random chance.
A specious argument to say the least.
1) The appearance of design does not demonstrate actual design.
2) Actual design does not desmonstrate a designer.
The above two can be readily demonstrated by crystals: they are the most ordered things in the known universe, yet they are not designed.
3) Simply
claiming that random chance* cannot account for the patterns in the known universe does not make it so.
The theory of common descent is a spectacular example of this: reproduction with variation
. That's it. That explains how the majesty of modern biodiversity can arise from obscenely simple systems.
This isn't just the fact that if you look at the sky at night there is beauty, and also beauty all the way down to the microscopic, but also statistical facts. Like the ''fine tuning'' of the universe is so improbable that there must be 'something' that guided the universe to life.
You're going to have to make more than romantic appeals to ignorance, I'm afraid.
Eg: the 'fine tuning' of gravity alone is 1 in ten thousand billion billion billion billion.
What on Earth does this mean? The force of gravity has a specific value, but what is this '1 in 10^40' ?
Also the fact that there is order, when there could have been chaos; there is no reason that we should have the laws just right so that they keep stars and planets together.
Think of it this way: why do we
only have stars and planets? The visable universe is full of gaseous bodies and rocky bodies, and not much else. Why is the universe so bland?
It should also be pointed out that amorphous blobs of hydrogen plasma don't constitute divine order.
Then there is the evidence for Jesus Christs life, death, and resurrection. In very short (ask if you want more detail), the fact that Soul/Paul became a follower of the 'dead' Jesus. The fact that no one knew where the body of Jesus was when no one could have stolen it. The fullfilment of prophecies. And the faith of the disciples.
I don't believe that Jesus existed at all, let alone was of divine origin and was resurrected. But by all means, convince me otherwise.
Personally for me, all that helps, but are not the reason I believe in God. I fine it obvious that God is very real, but I know this is not true for all people. Through my life I have had it proven time and time again that Jesus lives and is the Son of God. I have seen healings, prophecies come true, God work in my life, prays answered and I know my life wouldn't be the same. Just about 3 weeks ago there was a woman in our church who, when people pray for her, her knee was out of the right place for some reason(I think it had been like that for years) and she felt a warmth in her leg, her knee moved to a normal position, and she was healed.
Numerous studies have shown that the alleged healing power of Christianity is, at best, a placebo, and at worst a discourager from
actual medicinal care.
*As opposed to what? Predetermined chance?