Does "its" refer to "religion" or does it refer to "spiritualism"?

Does "its" refer to "religion" or does it refer to "spiritualism"?

"have been brought back by its means...."

It is no unusual thing for struggling and distressed souls to be helped through Spiritualism. Do we not all know people who had given up all religion and who have been brought back by its means? Agnostics who had lost all hope of God and immortality, to whom religion seemed mere formality and dry bones, and who at last turned upon it and reviled it in all its manifestations. Then Spiritualism came....


"The History of Spiritualism," by Sir Arthur Conan Doyle