'pro-church' is a compound formed from the prefix 'pro-' and the noun 'church'. 'Pro-' originates from Latin, specifically the word 'pro', where 'pro' meant 'for'. 'Church' originates from Old English 'cirice', ultimately from Late Greek 'kyriakon', where 'kyriakón' meant 'of the Lord'.

'church' changed from Old English 'cirice' (from West Germanic *kirika), borrowed from Late Greek 'kyriakon', and eventually became the modern English word 'church'. The prefix 'pro-' comes from Latin 'pro' and has been used in English as a productive prefix meaning 'in favor of' or 'for'.

Initially, components referred to 'for' (pro-) and 'the Lord's (house)' (kyriakon → church). Over time the compound 'pro-church' has come to mean 'in favor of the institutional church or its authority' rather than a literal 'for the church building'.