Evangelical churches in Cuba are campaigning against a proposed constitutional change that would open the door to same-sex marriage.

In July, Cuba's National Assembly approved a draft constitution that would allow gay couples to marry in Cuba. The public will weigh in through a consultation to be held later this year.

The constitutional change is being spearheaded by Deputy Mariela Castro, the daughter of Communist Party chief Raul Castro and the head of Cuba's National Center for Sex Education.

According to Reuters, a group of 21 evangelical denominations have started gathering signatures for a petition against the amendment, titled Article 68.

“We do not in any way approve Article 68 … because the Bible condemns it,” Pastor Lester Fernandez told a cheering crowd of around 500 people earlier this month.

The campaign includes posters celebrating the “original family design, just as God created it” plastered on church doors and windows.

Reuters noted that the campaign in a country that once jailed religious people, as it did gays, has surprised many people. Cuba does not officially recognize LGBT activists, making them unable to launch their own campaigns in favor of the amendment.

The Roman Catholic Church has also expressed its opposition to marriage equality, but has yet to organize against the proposed amendment.