Before: "Nichiren believed his purpose was to spread Buddhism; Nichiren’s Buddhism could be spread only by the Lotus Sutra. The belief in the sutra was of the utmost importance, as well. If one did not devote themselves to this sutra, they would surely be reborn in a hell realm in the next or a not too far off life."
After: "Nichiren believed his purpose was to spread Buddhism; Nichiren’s Buddhism could spread only by way of the Lotus Sutra. The belief in the sutra was of the utmost importance, as well. If one did not devote themselves to this sutra, they would surely live in a hell realm in the next or a not too far off life."
For this one, I didn't have many things I could feasibly change. I learned this in HS so I avoid "be" except in cases of "to be..." things.