From God and Man by Metropolitan Anthony of Sourozh (aka Metropolitian Anthony Bloom), published by Darton, Longman, Todd, 2004 edition, pgs 45-47 :

…concerning faith, one preliminary remark. Faith is very often understood by people as a defeat of intelligence. In other words, faith begins when I can no longer think creatively when I let go of any attempt at rational understanding, and when I say ‘I believe’ because it is so absurd that it is the only way of facing the problem. This may be an act of credulity, it may be an act of cowardice, it may be a preliminary act, full of wisdom and intelligence, that teaches us not to draw conclusions or to come to conclusions before we have understood. But this is not faith as understood by the great men of all religions, and particularly the Christian faith. In the Epistle to the Hebrews in the eleventh chapter faith is defined as ‘certainty of things unseen’. We usually lay the stress on ‘things unseen’ and forget the ‘certainty’ about them. So when we think of faith we usually think of the invisible and instead of  certainty put against it an interrogation mark. Then to solve the problem we accept in a childish way, in an unintelligent way very often, what we are told by others – usually our grandparents of three generations back or whoever else we choose to believe for reasons that are not always reasonable. But if you try to see the way in which faith originates in those people who were the great men of faith, the heroes of faith, you can see that it always originates in an experience that makes the invisible certain, and which allows them, having discovered that the invisible is as real as the visible, to go further in searching the invisible by methods of their own.

There is a passage for instance, in the works of Macarius of Egypt, a man who lived in the fourth century. He says ‘The experience of God, the vision of the world in God, is something which can happen only at a moment when all our thoughts, all emotions, are arrested to such a degree that we can no longer both be within the experience, perceive the things, and step out of the experience, watch ourselves and analyse what is going on. The moment when an experience is “lived” is a moment when we cannot observe it.’ And he says that this would be quite sufficient for someone who has had an experience of God. He would not wish to go back to another stage. But he also says, ‘God has concern not only for those who have this experience, but also for the people who haven’t got it; that someone should come to them as a witness of things unseen, and yet experienced, real, and he steps back away from them.’ At that moment begins, as he says, the realm of faith. The certitude remains even though the experience is already of the past; the certainty is there because what has happened to him is as certain as anything around him, is tangible, visible, perceived by the senses, so that the moment of faith begins as a result of a first contact with the invisible, discovered, disclosed somehow.

That means that we must be very severe and sober when we speak of our faith, for we often say ‘I believe this and that’ when we have taken it from someone else that it is true – we don’t care to investigate it in depth, and as long as this truth or illusory truth is not destroyed or broken down, then we take it for granted. This is a bad faith; this is what one of our Russian theologians called ‘the aged sacrament of the faith that does not think’.

Very much worth pondering.