I say, and with God's help: If a Muslim is a caller to Allah, he should seek to visit Christians in order to spread his message and demonstrate the greatness and beauty of the Islamic religion; this is commendable. However, if the purpose of the visit is merely entertainment and wasting time, without any display of the virtues of the religion or a legitimate connection to a neighbor, it is better to avoid it for fear of being influenced by their ideas and behavior. And Allah knows best.