Jenna Jameson's Ex Jay Grdina -- Son Blackballed from Religious School ... Lawsuit Coming

The man once married to porn legend Jenna Jameson has just been blackballed from an exclusive private school ... a school which had already admitted his son and accepted his money, but sent a last minute rejection because they said his life was unholy.

Jay Grdina married Jenna in 2002 and together they created one of the most successful porn companies in the world -- Club Jenna. They divorced in 2006 and sold the company to Playboy for a reported $25 mil.

Jay moved on, married supermodel Erin Naas and moved to Scottsdale, AZ, where they had 2 sons.

Jay made even more money with his latest venture, NOHO, a drink to help prevent against hangovers.

Now fast forward to last December, when Jay and Erin sent a kindergarten application to Scottsdale Christian Academy for 5-year-old Jayden. In May, after multiple interviews, Jayden was accepted.

All was well until last Wednesday, the day before school began, when Jay got an email from the school, saying, "Unfortunately after a final review during our admission process, we are now unable to provide admission."

The email then got specific, "It has been brought to our attention that due to the lines of business that your family is/was in would violate these foundational critical issues of SCA."

We checked the SCA rules, and the foundational issues include "legal vices," including gambling, tobacco and alcohol. BTW, the foundational issues also say, "God's design for marriage is the union of one man and one woman."

Here's the big problem. Jay says all of the other schools have been up and running for a month, so they're scrambling, but Jayden will be far behind the other students. And he missed his first day of school.

Jay says he plans to sue SCA.