I read this book in the late 1980s or possibly very early 1990s. It was about the second coming of Christ but extremely blasphemous in its plot line (as far as I recall, Christ had come back as a very horny teenage boy and the second “coming” was a double-entendre).
I am in the U.K. and I think it was by a British author / set in Britain; I also think it may have been by a female author and/or told from the perspective of a female character. I believe it was a young adult novel and was recently published at the time I read it. I think the cover may have had a picture riffing off Michaelangelo’s “Creation of Adam” and it was a “normal sized” paperback novel.
Unfortunately Google results for “second coming” and related phrases are swamped with unrelated results.