This contribution discusses Leibniz’s conception of the Christian church, his life-long ecumenical efforts, and his stance toward religious toleration. Leibniz’s regarded the main Christian denominations as particular churches constituting the only one truly catholic or universal church, whose authority went back to apostolic times, and whose theology was to be traced back to the entire ecclesiastical tradition. This is the ecclesiology which underpins his ecumenism. The main phases and features of his work toward reunification of Protestants and Roman Catholics, and (...) unification of Protestant churches are briefly explored, before turning to the issue of religious toleration. It is argued that a remarkably inclusive conception of toleration can be gleaned from a broad sample of Leibniz’s writings and correspondence. It is thanks to the philosophical and theological grounds of this conception that toleration can in principle be extended, for Leibniz, to all men and women of good will, including non-Christians, pagans, and atheists. (shrink)