From time to time, I receive queries about the subject of God's existence. My correspondents want to know what logical and scientific proof there is for God's existence.
Most intellectuals throughout history (especially before the modern period) likely have believed in God. An author named Max Fishler wrote a book on this very subject many years ago. Examples of theistic philosophers include Socrates, Plato, Aristotle, Georg Hegel, Immanuel Kant, and Soren Kierkegaard.
The philosophical (logical) evidence for God's existence is multifaceted. There have been numerous arguments put forward to prove there is a Supreme Being. But keep in mind that philosophical arguments generally are not apodictic (i.e. irrefutable or incontrovertible). No logical argument is airtight: fault can be found with almost every line of reasoning proferred. But Thomas Aquinas advanced the cosmological argument for the existence of God. See his Summa Theologica.
Aristotle sets forth proof for God's existence in his work Metaphysics (book 12). There is also the Kalam cosmological argument posited by the medieval Islamic philosophers and (in our time) by William Lane Craig.
The Kalam approach could be formulated this way: A) Everything that begins to exist has a cause; B) The universe began to exist; C) Therefore, the universe has a cause. Of course, the argument becomes lengthy and complex, so I merely give you the following as an example.
I believe there is scientific evidence that points toward the existence of God. I'm reading a complex book now that uses new insights from physics to argue for God's existence. One example is the second law of thermodynamics, which suggests that the universe has not always obtained. How did it come into existence? What is the most reasonable explanation? Additionally, the fine-tuning of cosmological constants might suggest that some intelligent entity made the precision of these constants possible. For example, the ratio of gases in the earth's atmosphere or the earth's tilt. Stephen Barr has written an interesting work on the relationship between faith and physics.