HAVANA, Oct 16 (Reuters) - Cuban evangelical churches are collecting signatures to petition against a proposed constitutional amendment that would open the door to gay marriage, as part of an unusually strong nongovernmental political campaign for the Communist-run island.

Cubans have been discussing the broader revamp of their Soviet-era constitution, as proposed by the Communist Party, at official block-level meetings nationwide since August.

Article 68, which redefines matrimony as gender neutral, has sparked a particular uproar, revealing how macho Cuban society remains despite making headway on lesbian, gay, bisexual and transgender (LGBT) rights in recent years.

Cuba's churches, which enjoy more autonomy and influence than any other organization not affiliated with the Communist Party after the country expanded religious freedoms in the 1990s, have been stoking the controversy. Read more via Openly