Many do not understand the concept of faith. They think that Christians are weak intellectually, believing with insufficient evidence. Atheists often adhere to an unproven underlying assumption, that reason is the highest way to find truth. They have not understood that faith is actually a very positive attribute. Jesus thanked God the Father for not just revealing His truth to the intellectuals, but for sending His gift of faith to the humble. He said, “I thank You, Father, Lord of heaven and earth, that You have hidden these things from the wise and prudent and have revealed them to babes” (Matt 11:25).
Bishop Kallistos Ware, in his introduction to the book “The Art of Prayer”, talks about three elements of man – body, soul and spirit. He goes on to say that body, soul and spirit each have their special way of knowing: the body, through the five senses; the soul through intellectual reasoning; the spirit can come to a mystical perception that transcends man’s ordinary rational processes.
What is implied in your question is as follows. Science has made very impressive progress. Atheists often claim that faith in God is a feeble attempt to “fill in the gaps”. In previous centuries thinkers would, for example, study the amazing beauty and order of nature, but could not explain how such order could have come about just by chance, so concluded there must be a creator. Belief in God filled this “gap”. Science then progressed: for example, Charles Darwin came up with the clever idea of “survival of the fittest”. Science had filled this gap, so there was no longer a need to invoke the concept of a creator. Your question implies that now that we have reached the 21st century, virtually all the gaps have been filled by science.
Thorough knowledge of science can lead to a different conclusion. Yes, science may have offered a plausible explanation for some gaps, but as science has progressed it has found other gaps. For example, modern physics has realised that it has no explanation for the amazing “biofriendliness” of the universe. There are about 30 basic parameters (e.g., the speed of light, Planck’s constant), which if they were a little different to their present values, would mean no life and certainly no humans. Scientists have done calculations and realized that if the speed of light or one of these other constants was only 1% more or less, or if the laws of physics did not happen to be exactly what they are, then there would be no life. The earth would not be continuously orbiting around the sun, there would be no carbon, therefore no DNA, and thus no life.
Another example is the so-called mind-brain debate. Even in the 21st century, no atheist has been able to come up with a convincing explanation of what philosophers call the “hard problem of consciousness”. We are aware that we exist, we can feel. An atheist believes that this can be “reduced” to physical processes occurring in our brains, that somehow out of the complex wiring of our brains there “emerges” self-awareness. They seem to start with the assumption that there is no God, they admit that currently we have no physical explanation for self-awareness, but conclude that there must be some physical explanation, that one day science and our imagination will progress and we will explain this gap as well. We in the Church however have received from God revelation that every human being has an immortal and eternal soul, which is closely connected with his body. The Church has a deep knowledge of human nature – man unites with his existence the tangible and intangible world.
Space does not permit me to give other detailed examples. We could have also referred to modern scholarly research on the “genre” of the Gospels: they do not have the features of “legend” but of “eye-witness accounts”.
In conclusion, an unbiased thinker can be convinced that it takes more faith to be an atheist than to be a Christian. We need to be humble and strive against the passions, we need philotimo, and to look into our faith with an open mind. We need to strive to truly pray and live the life of the Church. St Silouan was speaking from experience when he used to say, “It is one thing to know about God, and another to know God”. Jesus said, “Blessed are the pure in heart, for they shall see God” (Matt 5:8).