I feel/felt that the pilgrimage I had recently attended was the time for me to strengthen my faith and exert myself in the propagation of the religion.
Is the sentence natural? And which bold word should I use?
Remember - if you don't use correct capitalisation, punctuation and spacing, anything you write will be incorrect.
This doesn't sound very natural to me. How about something like make greater efforts to spread my religion?exert myself in the propagation of the religion
I'd be more likely to make or go on a pilgrimage rather than attend one.