A number of skeptics have said that Muffy created God. But God by definition is the uncreated creator of the universe, so the statement ‘Muffy created God’ is illogical, just like ‘The bachelor is married!’
So a more sophisticated questioner might ask: ‘If the universe needs a cause, then why doesn’t God need a cause? And if God doesn’t need a cause, why should the universe need a cause?’
Here is the reasoning:
Everything which has a beginning has a cause.
The universe has a beginning.
Therefore the universe has a cause.
The universe requires a cause because it had a beginning. God, unlike the universe, had no beginning, so doesn’t need a cause. In addition, Einstein’s general relativity, which has much experimental support, shows that time is linked to matter and space. So time itself would have begun along with matter and space.
Since God, by definition, is the creator of the whole universe, he is the creator of time. Therefore He is not limited by the time dimension He created, so has no beginning in time — God is ‘the high and lofty One that inhabiteth eternity’ (Isaiah 57:15). Therefore He doesn’t have a cause.
In contrast, there is good evidence that the universe had a beginning. This can be shown from the Laws of Thermodynamics, the most fundamental laws of the physical sciences.
1st Law: The total amount of mass-energy in the universe is constant.
2nd Law: The amount of energy available for work is running out, or entropy is increasing to a maximum.
If the total amount of mass-energy is limited, and the amount of usable energy is decreasing, then the universe cannot have existed forever, otherwise it would already have exhausted all usable energy — the ‘heat death’ of the universe. For example, all radioactive atoms would have decayed, every part of the universe would be the same temperature, and no further work would be possible.
So the obvious corollary is that the universe began a finite time ago with a lot of usable energy, and is now running down.
Now, what if the questioner accepts that the universe had a beginning, but not that it needs a cause? But it is self-evident that things that begin have a cause — no-one really denies it in his heart. All science and history would collapse if this law of cause and effect were denied. So would all law enforcement, if the police didn’t think they needed to find a cause for a stabbed body or a burgled house.
Also, the universe cannot be self-caused — nothing can create itself, because that would mean that it existed before it came into existence, which is a logical absurdity.
For more info: http://www.christiananswers.net/q-aig/aig-c039.html