This is only an introduction to the main arguments for God’s existence. Obviously, much more can and has been written. First, the question of evidence for God’s existence is not a matter of some evidence being for God’s existence and some being against. It is whether or not the existence of God explains all of the evidence better than the alternative (that, is, that there is no Being higher than us).
Second, we say that one’s own understanding of the concept of God is one strong piece of evidence. This is something which most people have no problem understanding even though most people also have a natural tendency to want to reject God (as I once did and all of us actually do by nature). This tendency shows that belief in God is not a matter of wishful thinking.
Third, there is the fact that you or anything else exists, since, as a contingent being, your existence must ultimately have come from some Necessary Being. Fourth, there is the amazing intricacy and capabilities of even simple forms of life. For example, a common house-fly is a far more advanced flying machine than anything we have been able to design. To say that the emergence of such life did not require design, but only mindless natural forces operating over a vast period of time violates the principle of Occam’s Razor, which says that, all things being equal, the simplest explanation is usually the correct one. The naturalistic explanation can only be surmised, never observed. But we constantly observe how the application of intelligence on matter produces complex items. Indeed, in the absence of efforts guided by intelligent purpose, the natural tendency of matter is to go from order to disorder (as anyone who never cleans their house will easily recognize!).
Fifth, the dominant belief today that the universe ultimately consists only of mindless matter/energy in time cannot explain the existence of us as people and any of our knowledge, experience or values (including all ethics). Sixth, ethics can only be arbitrary unless there is a Higher Standard. The only reason good and evil are not arbitrary is because goodness is God’s Nature as The Perfect Being. Anything which contradicts or opposes this is evil. (I would add that the only reason God can truly be self-sufficient as a Person is because He is relational within His own Being as multi-Personal. This shows the superiority of Christian Monotheism.)
Even if one were to claim that all of our experience as human beings is only an illusion, this still wouldn’t eliminate the fact that we still exist as real subjects of the illusion! And, taken to its logical conclusion, the anti-Theistic alternative absurdly posits an empty universe of objects with no knowing subjects. In other words, your existence as a human person disproves the Materialism/Empiricism of Atheism. For example, unless we existed as more than physical chemistry, a person looking at their own brain chemistry could only be described as chemistry somehow viewing itself! This is the “reductio ad absurdum” of Materialism (also known as Naturalism, which is supported by the equally-flawed epistemology of Empiricism).
All of these things point to the necessary existence of The Creator God described in the Bible. They are not necessary proofs in the respect that God’s existence needs to be established by proof. God is not a theorem. He is The Ultimate Fact. In fact, even logic itself is not explainable without the existence of The One True God (as the way His Mind works and the way ours is supposed to work because we have been made in His likeness). So, God must exist or else we couldn’t prove anything.
Thus, all of these “proofs” are not really proofs, but “evidence after The Fact” of something which is above all proof: God’s inescapable existence. But most people “can’t handle the truth!” that God exists because they want to be the god of their own lives. The Bible calls this our “sinful nature”, by which we are naturally-inclined to reject God. This is despite the most direct piece of evidence of all: the fact that all of us inevitably and inescapably know The One True God in our hearts, but suppress this knowledge.
Many reading this will undoubtedly deny that you already know God exists, just as you will likely resist where all of the above evidence points. But that is simply you acting according to the basic characteristic of mankind, as the Bible alone explains it: because you were born as a member of a rebellious race of sinners. Only God can change this, but all of us are culpable for not seeking Him and asking Him to open our hearts, eyes and minds so that we can get to know Him and so that we can be saved and transformed. The Gospel found in the Bible explains this and has led millions to The Greatest Blessing possible: the peace and joy of knowing that I have been forgiven of my sins and that my Creator loves me with perfect love.
I hope and pray that you will truly consider all of this and find the same Blessing which I found 32 years ago.