He seemed a bit surprised when I suggested to him that he could have turned the question around and asked the atheist, "What if you get to the point of death and find out that He does exist?"
There is a sense in the heart of many of the unconvinced that they are secure in their philosophy of life. Nothing too tragic has occurred to them except for the common events of the human existence. They find pleasure in their pursuits. They feel empowered and in charge. They scorn the weaknesses of those who "need" to have a "god" in their lives. In fact they feel like they triumph over the Christians they see. They exist, and they are convinced there is no omnipotent being watching over them.
The Babylonians felt the same way. They had conquered God's people and taken them into captivity. They were the "Queen of Kingdoms." Even though God made it clear that the downfall of Judah was His doing and not theirs, they felt confident. Their magic was working for them. Now God warns them:
You have trusted in your wickedness and have said, ‘No one sees me.’ Your wisdom and knowledge mislead you when you say to yourself, ‘I am, and there is none besides me.’ Isaiah 47:10
They were about to go down and they were so deceived they could not see it. They were misled by their "wisdom and knowledge." They thought the world revolved around them and they neglected the knowledge of God. Romans 1 reminds us that God turns folks like that over to their delusions so that they may see the error of their ways and turn to Him.
We all have many friends and acquaintances who are being misled. At some point you may be in a conversation with them where they suggest you are foolish for following Christ while they are just fine and enjoying the life they have. Tuck this question away and the Holy Spirit may prompt you to ask them when appropriate: "But what if you get to the point when you die and you find He is real? What then?"
This life is but a blip on the radar of eternity. I'd rather be a "fool" during the blip than face an eternity apart from Christ.