Throughout my life I have heard many unbelievers express the question whether or not there is a God. They are constantly looking for the answer, so it seems, but in reality they are looking for an excuse for their unbelief. Many citing that if there was a God, then He would make himself known unto them.
However, Paul says, that what may be known about God is clear to see because God has indeed revealed himself to us. As the plan from the beginning God's desire was always to come into relationship with us and abide and fellowship with us. He choose us and in the same way, He wanted us to choose Him, therefore He unequivocally revealed Himself to us, so that we can know without a doubt that He exists.
On the other hand, countless times I have talked to believers and in sharing their testimony with me one theme rings loud and clear. Most every one I have talked to started with a desire as a very young child to know God. Many described how they knew from their youth that God was drawing them unto Himself and revealing Himself to them. They longed to know Him and fellowship with Him.
Some of them accepted God's invitation right away. Some did their own thing for a very long. But each one remembered back to that time when they knew that God existed and that He had made himself known to them. This bearing witness to what Paul declared, God has indeed made himself known unto all humankind.
It is God's desire that you know Him. Not just that He exists even though he has clearly revealed himself to us. His desire is to know you intimately and have relationship with you. He wants you to know Him intimately also. So much so, that He provided the way for you to come into fellowship with him, through His Son Jesus' dead on the cross and resurrection from the dead. Today, May you know without a doubt that God exists and that He loves you immensely.