The head of the Catholic Church in Portugal has advised Portuguese women to think twice before marrying a Muslim. Cardinal Jose Policarpo said late Tuesday that Christians should learn more about Islam and respect Muslims. But he said marrying a Muslim man can bring "a whole lot of trouble" because Christian women become subject to Muslim conventions. "Think twice before marrying a Muslim, think very carefully," Policarpo said in the comments broadcast widely on Portuguese media Wednesday. "You can get into a whole lot of trouble, and not even Allah knows where it might end." Policarpo said it was "very difficult" to engage in discussion with Muslims, but insisted the Portuguese church has warm relations with the country's Muslim population of around 100,000.