On Sunday Joshua Harris, author of the popular Christian relationship guide I Kissed Dating Goodbye, posted Instagrams from the festivities. “An American in Canada marching with the British Consulate in the Pride Parade,” one caption read.

He also shared a photo of himself alongside LGBT advocates, including out rocker Trey Pearson and Queerology podcaster Matthias Roberts.

Harris, senior pastor of Covenant Life Church in Gaithersburg, Maryland, from 2004 to 2015, first came to notice as a 21-year-old in 1996 with I Kissed Dating Goodbye, a biblical guide to relationships that advocating courtship and abstinence before marriage rather than modern dating and casual sex.

A leader in the purity movement, he also wrote Boy Meets Girl: Say Hello to Courtship and Sex Isn’t the Problem: Lust Is.

But on July 26, Harris posted on Instagram that he had undergone “a massive shift in regard to my faith in Jesus.”

“The popular phrase for this is ‘deconstruction,’ the biblical phrase is ‘falling away,” he added. “By all the measurements that I have for defining a Christian, I am not a Christian.”

In the same post, he specifically apologized for his previous opposition to same-sex marriage and LGBT rights.

“To the LGBTQ+ community, I want to say that I am sorry for the views that I taught in my books and as a pastor regarding sexuality. I regret standing against marriage equality, for not affirming you and your place in the church, and for any ways that my writing and speaking contributed to a culture of exclusion and bigotry. I hope you can forgive me.⁣⁣”

He also walked back the views on dating he espoused in I Kissed Dating Goodbye.

“While I stand by my book’s call to sincerely love others, my thinking has changed significantly in the past 20 years. I no longer agree with its central idea that dating should be avoided. I now think dating can be a healthy part of a person developing relationally and learning the qualities that matter most in a partner.”

And Harris shared that he and his wife, Shannon, were splitting up but “will continue our life together as friends.”

On Twitter, Harris identified himself professionally as working in “marketing, branding and content strategy.”

A post shared by Joshua Harris (@harrisjosh) on Jul 26, 2019 at 12:04pm PDT

Evangelical leaders have responded to his “falling away” from Christianity with a mix of anger, sadness and confusion.

Pastor Heath Lambert, author of Finally Free: Fighting for Purity with the Power of Grace, announced he was removing Harris’ forward from the book.

“In Finally Free, I am trying to be clear about a Christian approach to sexuality,” Lambert said in a statement. “Joshua’s recent actions and statements only confuse that attempt at clarity and will lead others astray.”

Harris “is in absolute spiritual peril,” Lambert added. “He needs our love, and he needs our prayers. He has mine, and I trust he will have yours as well.”