4 Today, in many parts of the world, under the inspiring grace of the Holy Spirit, many efforts are being made in prayer, word and action to attain that fullness of unity which Jesus Christ desires. The Sacred Council exhorts all the Catholic faithful to recognize the signs of the times and to take an active and intelligent part in the work of ecumenism. The term "ecumenical movement" indicates the initiatives and activities planned and undertaken, according to the various needs of the Church and as opportunities offer, to promote Christian unity. These are: first, every effort to avoid expressions, judgments and actions which do not represent the condition of our separated brethren with truth and fairness and so make mutual relations with them more difficult; then, "dialogue" between competent experts from different Churches and Communities. At these meetings, which are organized in a religious spirit, each explains the teaching of his Communion in greater depth and brings out clearly its distinctive features. In such dialogue, everyone gains a truer knowledge and more just appreciation of the teaching and religious life of both Communions. In addition, the way is prepared for cooperation between them in the duties for the common good of humanity which are demanded by every Christian conscience; and, wherever this is allowed, there is prayer in common. Finally, all are led to examine their own faithfulness to Christ's will for the Church and accordingly to undertake with vigor the task of renewal and reform. When such actions are undertaken prudently and patiently by the Catholic faithful, with the attentive guidance of their bishops, they promote justice and truth, concord and collaboration, as well as the spirit of brotherly love and unity. This is the way that, when the obstacles to perfect ecclesiastical communion have been gradually overcome, all Christians will at last, in a common celebration of the Eucharist, be gathered into the one and only Church in that unity which Christ bestowed on His Church from the beginning. We believe that this unity subsists in the Catholic Church as something she can never lose, and we hope that it will continue to increase until the end of time. However, it is evident that, when individuals wish for full Catholic communion, their preparation and reconciliation is an undertaking which of its nature is distinct from ecumenical action. But there is no opposition between the two, since both proceed from the marvelous ways of God. Catholics, in their ecumenical work, must assuredly be concerned for their separated brethren, praying for them, keeping them informed about the Church, making the first approaches toward them. But their primary duty is to make a careful and honest appraisal of whatever needs to be done or renewed in the Catholic household itself, in order that its life may bear witness more clearly and faithfully to the teachings and institutions which have come to it from Christ through the Apostles. For although the Catholic Church has been endowed with all divinely revealed truth and with all means of grace, yet its members fail to live by them with all the fervor that they should, so that the radiance of the Church's image is less clear in the eyes of our separated brethren and of the world at large, and the growth of God's kingdom is delayed. All Catholics must therefore aim at Christian perfection and, each according to his station, play his part that the Church may daily be more purified and renewed. For the Church must bear in her own body the humility and dying of Jesus, against the day when Christ will present her to Himself in all her glory without spot or wrinkle. All in the Church must preserve unity in essentials. But let all, according to the gifts they have received enjoy a proper freedom, in their various forms of spiritual life and discipline, in their different liturgical rites, and even in their theological elaborations of revealed truth. In all things let charity prevail. If they are true to this course of action, they will be giving ever better expression to the authentic catholicity and apostolicity of the Church. On the other hand, Catholics must gladly acknowledge and esteem the truly Christian endowments from our common heritage which are to be found among our separated brethren. It is right and salutary to recognize the riches of Christ and virtuous works in the lives of others who are bearing witness to Christ, sometimes even to the shedding of their blood. For God is always wonderful in His works and worthy of all praise. Nor should we forget that anything wrought by the grace of the Holy Spirit in the hearts of our separated brethren can be a help to our own edification. Whatever is truly Christian is never contrary to what genuinely belongs to the faith; indeed, it can always bring a deeper realization of the mystery of Christ and the Church. Nevertheless, the divisions among Christians prevent the Church from attaining the fullness of catholicity proper to her, in those of her sons who, though attached to her by Baptism, are yet separated from full communion with her. Furthermore, the Church herself finds it more difficult to express in actual life her full catholicity in all her bearings. This Sacred Council is gratified to note that the participation by the Catholic faithful in ecumenical work is growing daily. It commends this work to the bishops everywhere in the world to be vigorously stimulated by them and guided with prudence.
Source: Unitatis Redintegratio (Vatican.va)