The Ashley Madison scandal has claimed another notable Christian scalp with the admission by theologian Robert Craig Sproul Jnr that he had visited the adultery website.

Sproul's father – also RC Sproul – is the Reformed theologian and pastor who founded Ligonier Ministries, where his son is a teaching fellow.

A widower, Sproul Jnr is the father of eight children and one grandchild and holds the chair of philosophy and theology at Reformation Bible College.

He has been suspended from both teaching positions following his admission.

He wrote on his blog: "In August 2014, in a moment of weakness, pain, and from an unhealthy curiosity, I visited Ashley Madison. My goal was not to gather research for critical commentary, but to fan the flames of my imagination. There I found two gracious judgments. First, I felt the grace of fear. Second, I felt the grace of shame. I was there long enough to leave an old email address. And within minutes I left, never to return. I did not sign up for their service or interact with any clients. I have always remained faithful to my wife even after her passing."

He said that he had repented and received forgiveness. However, he added: "With the revelation of the hack has come the revelation of my sin. I recently informed the board of Ligonier Ministries, which has handled the matter internally, having suspended me until July 1, 2016. I also informed my presbytery which is also handling the matter internally. And now the world is informed.

"My sin, sadly, has impacted those who are innocent – my colleagues, friends, and family. I have and will continue to seek their forgiveness. I covet your prayers."

The Ashley Madison hack has resulted in the release of millions of user emails into the public domain. While many are thought to be false, the release has had devastating effects on some families, with some suicides reported.

Family life campaigner Josh Duggar and blogger Sam Rader have both admitted using the site.

The executive director of LifeWay Research, Ed Stetzer, said last week that he estimated that "at least 400 church leaders (pastors, elders, staff, deacons, etc.) will be resigning Sunday".

Stetzer said: "This is a significant moment of embarrassment for the church – and it should be."