Occasionally in apologetics, Christians ask atheists to complete the statement “God does not exist because…” The answers vary. The goal is to cross-examine those arguments, find inconsistencies in them, and then attempt to demonstrate that atheism can not be rationally supported. I think it is an interesting and profitable approach.
As a result, some atheists have turned the statement around and applied it to Christians. They ask them to complete the sentence, “God exists because…” Their goal is similar to the Christians’. They want an opportunity to expose the fallacious argumentation presented by Christians and further justify their atheism.
Is it fair for the atheists to ask the same question ‘in reverse’? I believe it is. So, let me propose an answer.
God exists because it is His nature to exist
There you go, God exists because it is His nature to exist. However, I need to clarify something. I’m a Christian Trinitarian. So, I’d respond and say, “The Christian Trinitarian God exists because it is His nature to exist.” That modification separates it from any other god concepts that might be raised by atheists.
Now the average atheist may not be satisfied with this response. If so, then I would ask that he demonstrate why it is not the Trinitarian God’s nature to exist. That would be impossible. An atheist could only deny God’s existence and would then be subject to completing the request, “God does not exist because…” Nevertheless, God’s nature is simply what it is. And since He exists, then it is His nature to exist. This is reflected in Scripture.
Exodus 3:14, “God said to Moses, ‘I AM WHO I AM’; and He said, ‘Thus you shall say to the sons of Israel, “I AM has sent me to you.”‘” (See https://www.blueletterbible.org/kjv/exo/3/14/t_conc_53014)
Psalm 90:2, “Before the mountains were born, or You gave birth to the earth and the world, even from everlasting to everlasting, You are God.”
In Exodus 3:13, Moses had asked God what His name was. God responded by saying, “I AM WHO I AM.” That is an interesting answer. Instead of giving what we would call a proper noun like Bob or Frank, God identifies His name with His self-existence, simply existing. In fact, the Septuagint writers translated the Hebrew “I AM WHO I AM” into the Greek, ἐγώ εἰμι ὁ ὤν, ego eimi ho on, which is ‘I am the being,” or “I am the one who exists.” For more on this see, https://www.blueletterbible.org/lxx/exo/3/14/t_conc_53014.
So, the answer is simple. The Christian Trinitarian God exists because it is His nature to exist. It is His nature to be the ‘being one.’
Part of the response to the challenge is to examine how the word ‘because’ is used. How is meant? Does it mean “because of that which caused God to exist”? Or, “because we can give you reasons that justify why God exists”?
In Christian theology, nothing caused the Trinitarian God to exist. So we cannot use the first sense. There’s a problem with the second sense because we Christians do not subject the Trinitarian God to our reasoning to justify His existence as if our reasoning validates it. Rather, He exists because it is His nature to exist. God never defends His existence in Scripture. He simply asserts it.