There is no conundrum there, whatsoever. God has not charged Christians, his children, with any burden to prove God's existence, omniscience, omnipotence, omnipresence, etc. to those who do not so believe. Yes, God has commanded Christians to do some things and to follow certain tenets, but has not given them the responsibility to stoop to the level of trying to PROVE anything about God to the non-believer. There is a separate and essential concept at work. Non-believers do not exhibit the capacity to grasp and employ that concept.
