Christians must work together to offer the faith they share to a world that seems to find it more and more difficult to believe, Pope Benedict told Catholic, Orthodox, Anglican and Protestant leaders.

“In today’s society, it seems that the Christian message has a diminishing impact on personal and community life, and this represents a challenge for all churches and ecclesial communities,” the pope said in his homily at an evening prayer service at the end of the Week of Prayer for Christian Unity Jan. 25.

Christian unity, he said, is almost a requirement for preaching to those who do not know Jesus or who have forgotten the “precious gift” of the Gospel.