Hope begins in the dark, the stubborn hope that if you just show up and try to do the right thing, the dawn will come. You wait and watch and work: you don't give up.
I sometimes feel that if your book sells more than 20 years, then there's something in it that you can say, gee, I did something that endures, that's timeless.
We know something of the history of the spread of Christianity, but much passed from recorded memory and much was transmitted by tradition whose accuracy has been repeatedly questioned.