Feeling lost

So I'm having surgery soon to remove a brain tumor. There's a significant likelihood that it's an aggressive cancer and that my prognosis will be a big fight ahead until I win or lose.

I was raised Catholic but have been non-practicing for a few years. I try to live the virtues and morals instilled in me even though many of the followers of Catholicism do not always. I've lost my faith in organized religion.

I feel like I have a hole that I've dug myself and cannot fill. Maybe it's a false comfort, but the thought that God is by my side was a comfort that I no longer feel... And now I'm a bit frightened. I feel desolate.