For Judaism and Christianity, Yale offers two intro courses (admittedly, they are more about the scriptures, not the religions per se): 1. https://oyc.yale.edu

For Judaism and Christianity, Yale offers two intro courses (admittedly, they are more about the scriptures, not the religions per se): 1. https://oyc.yale.edu/religious-studies/rlst-145 https://oyc.yale.edu/religious-studies/rlst-145 2. https://oyc.yale.edu/religious-studies/rlst-152 https://oyc.yale.edu/religious-studies/rlst-152 They are also available in book form. For Buddhism, A History of Indian Buddhism: From Sakyamuni to Early Mahayana (インド仏教史) by Akira Hirakawa is the best one I ever read.