A Perth church has defended its decision to host a controversial supporter of "gay conversion therapy" in a public seminar about same-sex attraction planned for Saturday evening.

Perth City Church of Christ is hosting an event with James Parker, billed as a presentation on his experience as a "gay activist to husband and father through Jesus Christ".

Former gay man James Parker. Credit:Facebook

Mr Parker, a former gay man, is now married with children and a speaker promoted through Parousia Media, an organisation which "strives to bring the message of faith and formation to Catholics and individuals across Australia".

Mr Parker is set to deliver his presentation on Saturday evening at Perth City Church of Christ, and the event was promoted through Facebook.