is a Japanese researcher of early Christianity and Gnosticism. Arai is a Doctor of Theology Professor emeritus of University of Tokyo and Keisen University, and a member of The Japan Academy. He graduated (1962) at Erlangen-Nürnberg University in Germany.
Arai was a pioneer of the studies of Gnosticism after the discovery of the Nag Hammadi library.
Works
Early Christianity and Gnosticism (1971), Iwanami shoten
Jesus and his Age (1974), Iwanami shoten (shinsho)
New Testament and Gnosticism (1986), Iwanami shoten
Evangelium according to Thomas (1994), Koudansha
Nag Hammadi Library ed. (4 vol.), (1997–1998), Iwanami shoten
Jesus Christ, Part1, Part2 (2001), Koudansha
Collected Works of Arai Sasagu (10 vol. and addendum book), (June 2001 - June 2002), Iwanami shoten