All the philosophers of the world who had a religion have said in all ages: "There is a God; and one must be just." That, then, is the universal religion established in all ages and throughout mankind. The point in which they all agree is therefore true, and the systems through which they differ are therefore false.
And, from Ralph McInerny, writing for Leadership University:
I think of St. Thomas who on several occasions observed that a person need only look around at the world and gain the idea of God. The order and arrangement and lawlike character of natural events impose the idea.
The difficulty with this all but universal acceptance of the divine lies in the identification of God. that is, trees and wind, sun and the world itself have been identified with God, nor has it been necessary to choose among these possibilities. This diversity does not tell against the naturalness of the recognition.
Professor Ralph McInerny
"Why the burden of Proof is on the Atheist"