Belief is functionally different than non belief.
Belief in Truth is definitely different than not believing in truth.
I couldn't lose faith because I understand what it is our faith is in and thus realize nothing else can be valid.
You don't understand what our faith is in, and so your grasp of it is very superficial. You only see the created externals of faith, not the spirit that inspires these manifestations.
What is my religion? Sincerity of faith and charity. Where could I go after this? Self deception and apathy toward my neighbor? It would be like a dog returning to his own vomit and eating it for me to choose worldliness over godliness. Everything in this world is vanity, I gain no pleasure from it anyway. Even the things that bring brief enjoyment leave empty soon after. My fortress, my home, my rest is in God. My life's focus is to abide in God with both my heart and mind. In my walk.
What is life without God? Meaningless. Vain. Not even really life, but death. Endless suffering and no consolation. With God, I have my consolation. With God I can endure the suffering and even transcend it. Without God there is no reason for anything. It is an empty existence where life is simply the satisfying of the lusts of the mind and flesh. What else is there? Where is the motivation? Where is the conviction? Everything is done for the hell of it.