I apologise for joining the party after it's finished but, This argument does not explain the existence of God. As according to this argument, God must have a creator? I do believe the Bible says something like God always has been and always will be, in order to side step the issue the though. In which case, why should this question only be allowed to be applied to science and not religion? It would be very easy for a scientist to turn around and say "The universe and everything in it has always been and always will be" however, until it is proved, no scientist will claim such a thing. So I think it would be very silly to discount science simply on the cosmological argument.