Tomas Aquinas, who argues for the cosmological point of view. The cosmological argument states that all things in this universe have a cause, and since these causes cannot go on for ever there must be a first cause, i.e. God. He argues that there are five ways to argue for the existence of God, the first is the argument from motion. This states that everything in this world has certain potentials for motion. It also states that for these potentials to be met another object and motion must set off said potential. That object in turn would have to have been put in motion by something else, and so on and so on. All of this ultimately leading up to one object which started all this motion, that one being God.
The second argument he makes says that there are many things that happen in this world, and they are effects derived from a cause. The effects in turn can be the cause of something else and so on and so on. Yet nothing can be the cause of itself, so therefore there must be a first cause, that sets off other causes, in hopes of reaching an ultimate goal. Therefore the first of all the causes would be God.
The third argument Aquinas uses is that of possibility and necessity. This argues that everything in this world has possibility to be and not to be. So if there is the possibility that everything at one time or another cannot-be, then at one time there was nothing, because everything that could've been wasn't. Yet if there was nothing at one time, then there was nothing that could be, and so there would still be nothing. Therefore there had to be something that existed to cause all the possibilities of everything else. But to be necessary something has to have something else cause it's necessity, which has something else causing it. This as with everything else stated before cannot go on indefinitely, so there has to be a beginning which would be God.
The fourth argument says that there is a gradation of everything, and that at the top of every gradation there is a maximum of the genus.