Now, we are living in an age dominated by rational intellect. Rationalism looks down upon devotion as irrational, something akin to fanaticism, a kind of blind faith in something whose existence is doubtful. However, the spiritualists say that devotion is not blind faith though it is beyond empirical reasoning. They say one cannot demand physical proof for supra-physical realities.
Faith amounts to conviction that things which cannot be seen or proven with physical or sensory instruments of certainty can be real yet. Empirical evidences that we get from direct sensory perceptions or observation do not always lead to sure knowledge. There is nothing like pure empiricism. Things change as we gain direct experiences of realities hitherto unperceived.
Faith comes when we accept something as real although we are yet to know it with certainty of senses and observation. Faith is intuition; faith is intuitive knowledge. Faith is a spiritual element of the mind, coming up straight from the soul that knows and not a physical element of the senses. Intuition can be defined as direct grasp or awareness of the truth. It is an instinctive understanding of the truth where reasoning has no role to play. It can be understood or grasped instinctively; it cannot be explained. And for this, it cannot be dismissed as illusion of mind. Faith remains a hypothesis until it becomes knowledge through concrete experiences of the supra-physical realities.
While the skeptics may dismiss faith and devotion in God as blind the believers will never agree although the faith is still a hypothesis for them not yet founded on experiential knowledge. Yet, the believers will stick to their faith under all circumstances favourable or hostile that God not only exists but takes care of them.
There are many atheists who change and become theists or believers in God with ripening experiences of life. Similarly, many of the mystics had begun their spiritual journey through blind faith and then experiences started flooding them with and their hypothetical belief in God became experiential reality.