There are things that do not necessary require argument. Something cannot seize to be true whether people believe in it out not. The reason why a lot of people do not believe in the existence of God is because He has not revealed Himself to them personally.
But the thing with God is that it takes a heart that hungers and thirst after Him before He reveals Himself. That is why faith is needed in our Christian faith. The Bible made it known that without faith we cannot please God because whoever comes to Him must first of all believe that He is. How will someone that God is God if the person lacks faith in the first place?
God would never force Himself on anyone. But for as many that would come to Him with all sincerity and desire He is certain to reveal Himself to them. As humans we all have questions that may remain unanswered and may sometimes leave us in doubts, but this does not give us reason enough to disbelief in His existence.
If we need evidence all we need to do is look around at the works of creation that are surrounding us. The more we keep ignoring these presence of God and dismissing His voice is the more we reduce our chances of encountering Him.
