Then he joined the faith called as Jashin. Jashin is a religion that worshipped the deity of the same name. The aim of this religion seems to be just slaughter people. And anything less than utter destruction is considered to be a sin. Through experiments with Jashin’s secret technique, Hidan gained immortality.
In my opinion, Hidan would have been similar to Rock Lee in the past as he wasn’t seen using any traditional jutsu and that was the case because he could not. He may suffer from the same problem that Rock Lee has, that being that he cannot properly manipulate chakra within his body. All of his attacks either involved his scythe or were based around his occultism. Hidan only ever uses the curse technique: death controlling possessed blood, which acts more like magic than anything else.