An online protest against gay rights foe Franklin Graham aims to leave him sermonizing to an empty arena in Iceland.

According to the International Business Times, Icelandic protesters are reserving hundreds of tickets to Graham's appearance next month at the Festival of Hope at Reykjavik's Laugardalsholl arena in hopes of leaving him with an empty venue.

Graham, a leading evangelical figure and the son of evangelist Billy Graham, last year supported a constitutional amendment banning gay marriage in his home state of North Carolina. He also criticized President Barack Obama's endorsement of marriage equality, calling it a “sad day for America.” In a Piers Morgan Tonight interview aired in March, Graham said that legalizing nuptials for gay couples would be a “great mistake” for the United States.

(Related: Franklin Graham: Gay marriage would be a “great mistake.”)

Graham, who heads the international Christian relief organization Samaritan's Purse, reportedly is going to Iceland at the request of Icelandic churches. Next month's sold-out event is free but attendees must reserve a ticket.

Protesters said on social media that they were reserving seats to the event with no plans to actually attend.

Elvar Thormar, a software developer, announced on Facebook that he had reserved 500 tickets. The venue holds between 5,000 and 11,000 people, depending on configuration.

In 2010, Iceland extended marriage rights to gay and lesbian couples with little opposition and overwhelming public support. Iceland's first – and the world's only – openly lesbian prime minister, Johanna Sigurdardottir, retired from politics in May.

(Related: Iceland PM Johanna Sigurdardottir inaugurates gay marriage law.)