Some would say that God is not the only explanation for life in the universe. They would say that there are alternative explanations such as Evolution, which can, according to Darwinians such as Richard Dawkins, explain the origin of life and obliterate the need for a God as an explanation. A designer as described in the Teleological Argument by William Paley is not necessary, and the 'designed' universe is actually proven to be an evolved one. As Dawkins said, "intelligent design explains precisely zero" of what we know about life.
However, other people would disagree, asserting that God has to be the only and original explanation, for example Christian Creationists who reject evolution as an explanation for the existence of life entirely. Ultra-conservative Christians propose that the creation of the world was as exactly written in the Book of Genesis, and attempt to explain away evolutionary evidence; fossils are apparently the result of animals drowning in the year of Noah and the Flood. This is called Scientific creationism, formulated by Henry Morris, try to maintain events such as the Seven Days and the Flood in the bible to make evidence used by Evolution seem concurrent with Creationism. There is even a hypothesis that the multiplicity of languages in today's culture is due to the Tower of Babylon, rather than a cognitive development formed by the convergence of genetic interest between relatives.
Others suggest that there is no possibility of other explanations for the existence of life than God as there has to be a 'prime mover', a start to the chain that allowed evolution to begin, which must be expressed as an external being or a God. Even Dawkins, when pushed to question infinite regress, suggested that an intelligent being from another world may have "seeded life" on Earth. Aquinas in his teleological argument asserted that "inorganic objects cannot direct themselves" and that the world works as if harmonised by an intellligent designer, though as a follower of Aristotle, he may have believed in a 'prime mover', and not in the traditional christian God who created the world in seven days, as was believed by the church in Aquinas's time, the 1200s.
On the other hand, there are those who say that religion and science can actually work together, that both evolution and creationism may be compatible in some interpretations, although maybe not the Creator as in the traditional Judeo-Christian concept of Him. Accepting the theory of evolution foes not necessarily lead towards a rejection of God's involvement with the process. In Darwin's book, 'The Descent of Man', he even implied that nature is an intelligent force or perhaps a being which decides fate and orders the process of natural selection in his quote "rejecting that which is bad and preserving that which is good". This suggests that there is a plan to the universe which, according to Hans Kung, shows that the meaning of the universe can be discovered, as opposed to a universe which came about by accident.
Finally some believe that science and evolution have not replaced evolution, but only the myth and analogies of the Holy Books such as the Torah and the Bible. Religions such as Christianity can be maintained without the ignorant and closed-minded view of Fundamentalists who refuse to listen to the logic of Evolution. Even the Catholic Church has now embraced evolution as an explanation for our development, while placing God at the heart of our origin by placing simplistic living organisms on the planet.
In my opinion a God, an intelligent force, is the only possible explanation for the existence of life as the suggestion of infinite regress is an illogical thought to me. However not a God as described by the Judeo-Christian concept. I prefer to think of God in more deistic terms; a spark which gave life and burned out long ago. I could not say with any conviction that there is any other plausible explanation for life that a God in some form or other.