This is a very good question, I love everyone's replies too, it's so interesting to me. Now I think about it, I'm gutted I didn't think of this one, lol.

I believe in God completely. Although I adhere to no religion.
As others have roughly stated, for a God to be 'true' it has to have only two aspects to its original nature.

1. God is the creator of everything.

2. God understands everything to its deepest core. (Even every moment in time that may have led to a decision for instance).

Now because of this, we can literally wipe all religions out as being illogical, I will explain why.

Subsets that also apply to God through these two definitions can be logically thought of as follows.

Subsets of 1.

1a. As the creator of everything, God also created maths and physics as rules in which to 'run' this universe.

1b. Under the terms of creation by a creator, God is 'external' to our universe. This includes being 'above' physics, maths and time (as we know it in this universe), as they are apart of the rules created, meaning God already worked and existed, before they did.

1c. Having created everything in a way that could be alikened (but using science and maths) to a simple thought of creation. God is also apart of everything that has been created. God’s process, is the universal process.

Subsets of 2.

2a. A. God being 'above' time and physics, means that, in perspective to us, God would have a seemingly infinite amount of time. The rules would not apply as they do to us, so would be able to kind of rewind, fast forward and pause the universe. Taking all the time it needed to fully understand every aspect of everything. But God would be able to do this in what would appear as no time at all has passed, and without actually having created anything yet. So at the inception of the universe, God already knew how everything would pan out, because it had already been through every possibility of the universes development.

2a. B. Under the principles of ‘there is no movement without time’, we can deduce that time must be apart of God itself.
As God must at least have a ‘perception’ of its own ‘time’ to be able to continue to make the universe. Imagine time is to God, almost as blood is to humans. God can use time as easily as we can move our arms. When God formed, so did time.

2b. A. God having seen all of humanity and the potential and 'actual' decisions we could/would/will make, knows every aspect of humanity. God knows the ultimate truth of right, wrong and why we do what we do.

2b. B. Those who know do not punish, they teach.

Think of a teacher in a school setting. They do not just 'hand out' all the answers, they lead their students to find the answers on their own. Then confirm, praise and point in the next 'correct' direction if needed. You might consider a 'perfect' teacher as one that could simply point the student in a 'right' direction, which would then lead the student to learn everything there is to know about that subject and everything related to it. God knows all, so God only teaches.

2b. C. In terms of punishment, this is only done by humans when we don't know how to instill the lesson needed in any other way. We punish criminals because, as far as we are concerned they have had their chances and shown they are not willing to be apart of 'cooperative' or 'normal' society.
We ignore the fact they may have mental illnesses that could lead them to not understand or feel like they 'don't fit in' normal society. This is simply because we don't understand it and have no other way to deal with it. If we did, we would successfully rehabilitate every criminal 100% of the time and just let them back into society without fear they will re-offend.

Another way to imagine this is to imagine something really stupid that you did when you were young, that you wouldn't even think of doing now.

Let say you 'kicked a dog', at the time it may of seemed funny or like the right thing to do. Although, you observe that you have hurt it, or you tell someone and they show disgust then teach you it's wrong to hurt living things. You feel bad, you learn and that behaviour changes and becomes ingrained in to your personality.
Now if you saw someone kicking a dog, it disgusts you, you may even try to stop it. If you saw a dog now it would never even enter your mind to kick it (of course providing their is no actual threat, even then you may do everything in your power to avoid this).

God knows that these are the moments that teach us, and people are often led to decision through circumstance . So we are never punished.

2b. D. God has the ultimate knowledge of right and wrong. So then, to suppose that God would threaten humankind in anyway for simple lack of knowledge or difference of view would be a misrepresentation of the idea of God itself. The idea would have to be deplorable to God under the terms of its own existence.
Even if you spent your whole life being a murderer you would still not be punished, you would only be taught.

Now, as these violent and agressive people have twisted their world view up so much, the teaching necessary might even be a likened to a 'hell'. Although this hell would be personal for them and the lessons they needed to learn. Such as, if someone had caused a lot of and therefore fail to understand, loss, then they might repeatedly feel loss in order for them to learn what it really is. Although this would not be eternal, they will learn, because it is an instance catered to 'overcome' these things rather then wallow in them. There would not be unnecessary suffering for no purpose.

3.a. God created the universe as we know it, all of it. So exists “outside” of it's own creation, as well as being a part of it, as we are apart of the things we create. God is not physical in the same capacity as us, so the idea of finding empirical evidence of God is a rediculous one. God gives us affirmation through the very thing it created, us and our universe. People know God because God is always there, has always been there, will always be there. There is a clear distinction in the world of “higher” ways of being, refer back to (2.b. C). People know right or wrong, and choose to listen or not. God has made it so we have those choices, and are guided in a way that best teaches us the things we need to learn.

So to end, God is the all understanding, parent/teacher who has created this place for us to overcome our primality and arrogance. But knows that in order to do so must require no interference from 'outside' sources, including itself. As this would destroy the point of us learning through 'free will'. God does not punish or hate, God knows the better of everything and so only teaches and loves. God would never leave a single person behind, because to do so would mean a sense of uncaring, God always cares.

I have received personal certainty of God's existence for myself, over many years, and this is unlike any normal experience. From this my whole being was altered. In progressive stages, I have reached an intense realisation of the nature of our relationship with this incredible intelligence. My understanding is that we all exist in this life supported, mentored, and progressed by this entity, who tends us all with love and compassion. Through the life experiences we endure, we evolve into a harmonic state with God. This is the true purpose of this life, to learn and to evolve.

There are obviously many more connotations to these things, but that is the simplest form in which I could describe it, forgive me if you found it lengthy. Although, I will be editing this as my understandings change with the discovery of new information.

(Edit note, upon further deliberation of the relationship between God and time, I came to the conclusion that time must be apart of God).