But Myriam Duru, 37, a manager at a Tommy Hilfiger store, disagrees.
"I am Muslim, so I believe in God. I think it's not a problem for me to accept. I don't understand people who think that God exists and can say 'I'm against the happiness of people,'" she said.
Alexis Nys, a 58-year-old salesman, said he supports same-sex marriage "because at the end it's love that matters. Not old things and old fashions. I think we need to live like we should live today."
A law legalizing civil unions was introduced in 1999 in France under a previous Socialist government.
Known in France as the PACS (pacte civil de solidarite), the civil union agreement can be entered into by same-sex or straight couples and confers many but not all of the rights of marriage.