One time I was discussing the origin of the species with my friend who had previously brought me back to the church, and I was arguing in favor of evolution from a common ancestor (accelerated and manipulated by God, of course) while he was arguing in favor of a massive creation from which things degenerated, each creature containing "potential" for numerous other types of creatures similar but not identical to itself, with the amount of potential in each creature decreasing over the generations.
That theory sounded kind of silly to me, but now I realize that he's probably right... he didn't deny that evolution could happen; he simply said that no new species could appear through evolution, only changes in existing species!
So think about the universe in terms of thermodynamics... the second law of thermodynamics says that the entropy in any closed system will always increase. What's entropy? Well, it's basically homogeniety, or sameness. If all the universe were empty, for instance, entropy would be at a maximum. That's the way the universe was "before creation", so to speak. But then God created things, and since God is above nature, he has the power to reduce entropy, which he did then, and has done throughout history - we call these occurrences "miracles". The universe will then degrade over time - stars burn out, species go extinct, people grow old and die - but every so often God injects a shot of "anti-entropy drug" into the universe! God doesn't do that in huge ways very often, though, because he wants us to see that actions have consequences.
So what will the end of the universe look like then? Scientists tell us that one of the likelier possibilities is that the universe will just burn itself out - everything will become the same once again. That's almost like the Eastern philosophies of the "universal oneness". And that's what would happen were God not to intervene once again, once the universe (or at least humanity) has completely burned itself out! So the prayer asking Mary to "pray for us in the hour of our death" might not only refer to individual death, but death as a species. Once humanity has reached the point of annihilation, God will step in at the behest of all who have gone before (as described in Revelation where the departed saints have been pleading around the altar for ages) and rescue those who will accept his aid - all the rest (of whom I hope there are few or none) will be annihilated - but not by God's "punishment" or "wrath" - no, I think the "lake of fire" must refer to what remains of the earth after the apocalyptic war!
What does this mean we should do, though? Often I think the world is headed downhill - well, according to the Bible, as well as to science, I'm right! But does that mean I should study physics and start developing more powerful weapons of mass destruction in order to hasten the kingdom of heaven? No, while that would not affect my personal standing with God, it would not be what God wants me to do! It almost sounds like God is sadistic, but God wants the world to drag on as long as possible... not for any sadistic purposes, this is simply because the longer the world lasts, the more people there will be to join him in a relationship in heaven, which is what he's been seeking all along! What God wants me to do is to share my experiences with others so that they may come to know him through my testimony.
So yes, God has changed my life, and for the better, I'd have to say! If you don't know God or are confused about who he is, ask me or any other Christian - if we can't answer your question, we can at least point you in the right direction!