If theories of quantum mechanics or the big bang theory state that matter and/or energy can be created from nothing without a cause, then those theories are illogical. Come on, think about it. What you're saying is that at one point, nothing at all existed. And then, for no particular reason, matter and energy suddenly began to exist out of nothing. Think about it from the point of view of the nothingness. Start there, and tell me if you think that the universe becoming what it is now, starting from that point, without any cause, really makes sense to you. If it does, then you've got way more faith than I am able to have. Science has not shown that it could happen, and has convinced me that the opposite is true even before I was really aware of the Bible. Some scientists have merely theorized that such things are possible, without any evidence to back them up.
Let me address the argument about the still. You say that all I see is smoke rising from behind the curtain, and you are telling me that a 'still' is causing this to happen. It would take faith for me to believe that a 'still' is causing this smoke to rise up, but it would take simple logic for me to believe that SOMETHING is causing the smoke to rise up, and I could make logical guesses as to what the object is by observing the smoke. If there is a lot of smoke, I could logically conclude that the object causing it is somewhat large and uses a lot of energy. If it's a small amount of smoke, I could logically conclude that it's not using so much energy, though it may or may not be large. I can also conclude, since it's hidden by the curtain, that it's small enough to be hid by a curtain. If you were to describe the 'still' to me and it fit what I could logically deduce from the smoke, then my believing that a still was making the smoke would be faith, but a logical faith. But to see the smoke, and have someone tell me that there is nothing behind the curtain making the smoke, but that the smoke is appearing out of nothing (and giving me theories as to how this is possible) would be illogical for me to believe.
What I'm saying is that to look at the universe and deduce that there is some sort of timeless, supernatural, creative, intelligent force behind it is a logical conclusion, and to suppose that the 'God of the Bible' is this being is faith, but a logical faith. But for someone to tell me that the universe appearing out of nothing (and giving me theories as to how this is possible) would be illogical for anyone to believe.
So to see the smoke and deduce that something is creating it is as logical as seeing the universe and deducing that something created it. And concluding that whatever is making the smoke is something that makes smoke and is small enough to be hid behind the curtain is just as logical as concluding that the creator of the universe is supernatural, timeless, creative, and intelligent. To accept that a 'still' is what is causing this smoke, if a 'still' fits the criteria for what I am observing, would be faith, but a logical faith, just as to see the universe and decide that the 'God of the Bible' created it is faith, but a logical faith. To accept that the smoke is being created by nothing at all would be illogical faith, just as illogical as accepting that the universe has no creator.
You ask, 'How do you know God is good and the devil is bad? How do you know it's not the other way around? You must use a secular morality to decide this matter.' I say that we are born with the understanding that God is good and the devil is bad. No one teaches us that, but God has created us to know that. Even those who don't actually believe in God and the devil still understand this at least metaphorically, the same way we are born to know that love is good and hate is bad, that life is good and death is bad, and that forgiveness is good and condemnation is bad. Even satanists, whose beliefs are pretty much 180-degrees from what Christians believe, will agree that God is good and the devil is bad, though they favor the bad over the good.
You say, 'Science says "I don't know" where religion says "God."' Actually, science says "God", and those who refuse to accept the obviousness of this reality continue to say, "I don't know" and look for other answers. I'd say the ridiculous idea that 'it all happened without any sort of cause' is evidence of this.
You say, 'There's no reason I can think of that requires the universe to have a purpose, can you?' Of course I can. The fact that the universe is here, and it began to exist. Without a purpose, it would not be here. If you're going to believe otherwise, that's your choice, but it means that you have way more faith than I do.