The word ecumenical comes from a Greek word that means pertaining to the whole world. It primarily describes a pluralist religious ethic, though in Christianity it only applies to the Christian church, and describes the pursuit of unity in the Christian world, between Christian denominations, and the universality of the Church.
In the Catholic and Eastern Orthodox churches an ecumenical council is a council of nearly all bishops of the whole church, capable of infallible decisions on theological questions. Catholics construe "the whole church" as including only Catholics. Eastern Orthodoxy construes it as including only, and with the consent of all of, the Orthodox which, they contend, since the Great Schism, consists of only the Eastern Orthodox; they call the Patriarch of Constantinople the "Ecumenical Patriarch" and "first among equals" - he has juristiction within his patriarchate and in those other parts of the world without another patriarch.
Hinduism is a religion that is inherently ecumenical and teaches a fundamental doctrine of multilateralism in regards to truth and spirituality. Hinduism teaches that, in essence, all religious, philosophical and spiritual paths when followed with a common base of human morality and love will reveal truth to the seeker, regardless of professed creed.
In ecumenical dialogue, Catholic theologians standing fast by the teaching of the Church and investigating the divine mysteries with the separated brethren must proceed with love for the truth, with charity, and with humility.
In fact, opposition to ecumenism is closely associated with antagonism, in the case of Traditionalist Catholics, to abandonment of Latin in the celebration of Mass, and, in the case of Greek Old Calendarists (who speak of "the arch-heresy of ecumenism"), to abandonment of the Julian calendar.
Lutheran-Orthodox Dialogue in the Sixteenth Century The courteous and friendly correspondence, from 1573 to 1581, between the Lutheran Theologians of Tübingen and the Patriarch Jeremias II of Constantinople.
We saw the beginning of institutional ecumenism in the 1960's, with The World Council of Churches, mostly liberal mainline Protestant denominations who denied such essential doctrines as the inerrancy of Scripture and a literal, bodily resurrection of Christ.
The Baha'i cry for one world religion appeals to the ecumenical spirit of the age, especially in light of the continuing insistence that Baha'is are in perfect harmony with the Christian Faith.
Ecumenism's promise of "unity" is tempting, but it denies Christ and paves the way for the Antichrist and his new world religion.