Hundreds of posters were hung around the El Raval neighborhood of Barcelona encouraging Muslim men to take Christian wives, saying that they were permitted and encouraged to marry "honest and chaste women of the Book" (meaning Christians) for the purpose of increasing the population of Muslims in the region. The posters read "Brother, join in alliance with a Spanish woman, teach her that Islam is the only true religion. Islamic law dictates that the fruits of this alliance will follow Islam, which will further strengthen our community." It appears these posters are part of the "right-to-return" movement to "Restore Al-Andalus" -- that is, Muslim Spain.
Source: La Gaceta and Christenverfolgung