In Middle Eastern culture it is very normal to talk about religion. Many refugees expect and welcome the opportunity to talk about spiritual matters. Secular Europeans should not imagine that refugees share their cultural squeamishness about religious discussion.
Refugees should have their religious freedom protected. This means enabling them to practice their Muslim / Christian / Yazidi / other faith or not to practice any. This also means ensuring they have the chance if they wish to explore other faith perspectives and to change faith if they choose. Wherever they are, Christians should indeed remain “free to talk about their faith, in accordance with their own religious freedom. They do this carefully, with sensitivity and respect for others.” See the “Engaging with Muslims” resource page and the excellent Swiss Code of Conduct