83 I have mentioned the will of the Father and the spiritual space in which each community hears the call to overcome the obstacles to unity. All Christian Communities know that, thanks to the power given by the Spirit, obeying that will and overcoming those obstacles are not beyond their reach. All of them in fact have martyrs for the Christian faith. Despite the tragedy of our divisions, these brothers and sisters have preserved an attachment to Christ and to the Father so radical and absolute as to lead even to the shedding of blood. But is not this same attachment at the heart of what I have called a "dialogue of conversion"? Is it not precisely this dialogue which clearly shows the need for an ever more profound experience of the truth if full communion is to be attained?
Source: Ut Unum Sint (Vatican.va)