gnomon wrote:If our world was designed by an omnipotent and omniscient creator, then we must answer the obvious question : why isn't the temperature always perfect to suit all tastes? Either <A> the creator screwed-up the design, and must continually fiddle with the thermostat (fighting those hot & cold demons), or <B> the system design was intended to allow some personal freedoms, which require a range of choices and a variety of thermostat settings. Besides, if everything was perfect, what would motivate us to get off our duffs to adjust the thermodynamic and moral balance of the world---does God have to do everything for us?

As I'm so often fond of quoting Ethan Allen, I'll just repost a snippet of my usual cut and paste job:
Rather let us exaltedly suppose that God eternally had the ultimate best good of beings generally and individually in his view...This is something I fall back on countless times a day when my mind inevitably turns to pondering God and the universe. Since God doesn't feel it necessary to appear to us and tell us what His intentions were in creating the cosmos that He did, we can either suppose that God is mad, deranged, grossly imperfect... or simply knows what He's doing and has the best in mind for us no matter how little of The Whole we are able to take in from our exceedingly limited perspective here on earth.
I've entertained the former suppositions, that God is crazy, a lunatic, or seriously flawed. All those ideas brought little but restlessness and disquiet to my soul, and in fact seemed to encourage me towards despair at a universe that wasn't merely random, but the bizarre product of a celestial nutcase. We are what we worship, and assuming that there really is a harmony and order hidden within the seeming-senselessness of the universe by a God who ultimately has the best in mind for us has the consequence of encouraging harmony and order within our souls, I believe.
After all, God did not create a cosmic nursery wherein no one gets hurt and everyone gets what everyone wants without any effort or sacrifice. Evidently, God didn't think that was a good idea, and we ourselves can see that when people choose to live in such a fashion, they become lazy, spoiled, unbearable, and useless to the world around them. But some people insist that since the world wasn't made this way, God therefore cannot exist; as Paine said (though in reference to certain kinds of petitioning prayer), they consider God and say "Thou knowest not so well as I".
But in regards to the OP: it's hard to say definitively if God intervenes in human affairs or not. It's entirely possible that if He does intervene, it's for the best of us all, and certainly not in any way that would be contrary to the laws of physics or all other natural laws of the universe. It's a well-meaning but immense conceit to suppose that God would violate the laws and design of the universe He took the trouble to create in the first place for the wants or needs of a single individual, because what's then to stop us from going back to the cosmic nursery problem and rejecting God altogether?
However, it seems to me that human history is saturated with circumstantial evidence that appealing to the divine is (or simply can potentially be) useful. The history of the world's religions seem to indicate that requests to God/the gods can go answered after all, thought not all prayers will be answered, at least not as the pray-er wants. Most religions (particularly modern monotheistic ones) will go on to explain that God hears all prayers but answers them as He sees fit and knows best for us. Going by this much, at least, it would seem reasonable to conclude that God has the power and desire to intervene, but isn't going to reshape the universe for any one individual, or any group of them - we all have to live in the world He provided, not the one we'd like Him to provide instead.
As for myself, I do believe that God intervenes, but again not in any way that defies the laws of the universe He made. Furthermore, God's intervention depends on what is being asked for and the consequences of granting it, and in all likelihood is mostly or entirely limited to inspiration. In other words, asking God for the strength to face a certain challenge or the whole of one's day is one thing, asking God to make it snow on Christmas Day or instantly create worldwide peace is quite another. In the former, all that is asked for is help in using one's own already God-given ability to rise to and meet challenges; in the latter, God is being asked to change how the universe and human nature (respectively) function.
It's easy to fall into an
illusion of contol with prayer and the assumption that God intervenes in human affairs. I know I've seen it all too many times with Christian friends who insist that all they need to do is ask God for something and they'll get whatever they want (especially if it's something of great importance). God definitely isn't a genie. If God intervenes at all, He's not going to turn the universe upside-down for any one of us, especially when He's given us the ability to provide for all our own needs and wants from birth (with the obvious exceptions of those poor souls who are born handicapped, but then one can presume God has provided for them by giving us all the ability to reason and the desire to be altruistic, which many humans use to help care for those who need it).
For my own part, I pray (most) every day, asking God for the guidance to use the gifts He has given me and live honorably in His sight. Even if God doesn't give me any guidance, I know I can manage, simply because He's already given me the ability to reason and thus make decisions and be steadfast, etc. I deliberately choose to believe, because even if I'm wrong (and all I can do is rely on the natural abilities God has given me), it's still all good.