A Perth couple who believe homosexuality is a sin that can be overcome are locked in a court battle with a West Australian organisation which denied their application to become foster parents.

Byron and Keira Hordyk, who are devout Christians attached to the Free Reformed Church of Baldivis, claim Wanslea Family Services discriminated against them on the grounds of their religious conviction.

Devout Christians Byron and Keira Hordyk claim they have been discriminated against for their religious beliefs. Credit:Facebook

An earlier attempt by the couple to have their claim heard by the Equal Opportunity Commission was knocked back after the Commissioner dismissed their complaint as "lacking in substance", but it was referred to the State Administrative Tribunal at the Hordyks' request.

Late last year Wanslea's attempt to dismiss the SAT proceedings on the basis they were "frivolous, vexatious, misconceived, or lacking in substance" was denied, with the matter currently being prepared for hearing.