I posted about this series only the other day, and I'm already way behind, as Volume 8 was released in early December. But along with the latest volume, a revamped website (http://www.saint023.com/) was released with details of an upcoming animated feature.
It will be released in Japan on May 10th, and will produced be A-1 Pictures who recently did the Uchu Kyodai (a.k.a. Space Brothers) anime series. Jesus is to be voiced by stage and screen actor Mirai Moriyama (森山未来) and Buddha by singer, songwriter, actor Gen Hoshino (星野源).
You can follow the movie twitter feed here: https://twitter.com/saint023_movie
Plenty of more updates to come on this in the coming months, stay tuned.