Some disbelievers have articulated that God somehow must be demonstrated by a "scientific method", purposely ignoring that God is spirit. Do not listen to them. How do you measure and investigate something that is, by all indications, undefined in our three dimensional world? God did not create this universe to contain Himself or house Himself or accommodate Himself. He operates outside of space and time, also His creation. He is not bound or constrained by any facet or feature or force of the creation. Therefore, nothing defined within the creation can measure, inspect, or detect Him. How then does God expect mankind to respond to Him if He, i.e., His "Person", cannot be seen? This is what God has done:
1) God created man to inherently know that He exists (Ecclesiastes 3:11, Romans 1:20)
2) God has created the universe so that mankind could perceive that it was His doing (Psalm 19:1). This is demonstrated in the intelligent manner by which everything in the universe is made - whether the design of DNA or the design of matter and the laws of physics which direct its behavior. It is also demonstrated by the incredible beauty of the universe as a whole down to the smallest flower.
3) God communicated a message in order for mankind to know Who God is and what God expects. That message is the Bible.
4) The Bible is unlike any book ever. It was written over a period of 1500 years by 40+ authors, several languages and several countries. No contradictions exist amongst the 66 books comprising God's Word. Except that the Bible was brought together in a supernatural way through God's Holy Spirit, its very existence would be impossible.
5) The Bible consists of about 2500 prophecies, 2000 of which have already been fulfilled. The text of the Bible is 27% prophetic. All fulfilled prophecies have been fulfilled exactly as stated. No prophecy failed to be fulfilled. The remaining 500 prophecies are related to the end-times which are yet to come. This is a further and compelling demonstration of the miraculous and supernatural nature of the Bible.
6) All archaeological discoveries related to the Bible have only proven the Bible to be reliable. Locations, peoples, and events in the Bible are corroborated by such finds or if not eventually will be. Zero archaeological finds have proven any part of the Bible to be false. Again, the Bible is reliable.
7) The personal testimony of hundreds of millions of believers demonstrates that God is real in their lives. It is a fiction and wishful thinking that "mass hysteria" could account for this.
Given the above testimony of the Bible demonstrating its reliability and authenticity, one is compelled that within the Bible is the true message of our God Who loves us.