It is a sad ecumenism indeed when Catholics ill-treat other Catholics! (Furrow, 643)
I once told the Holy Father John XXIII, moved by the affable and fatherly kindness of his manner: 'Holy Father, in our Work all men, Catholics or not, have always found a welcome. I have not learnt ecumenism from your Holiness'. He laughed, for he knew that way back in 1950, the Holy See had authorized Opus Dei to receive in the Association as Cooperators people who are not Catholics or even Christians.
In fact there are many separated brethren who feel attracted by the spirit of Opus Dei and who cooperate in our apostolate, and they include ministers even bishops of their respective confessions. As contacts increase, we receive more and more proofs of affection and cordial understanding. And it is because the members of Opus Dei centre their spirituality simply on trying to live responsibly the commitments and demands of Christian Baptism. A desire to seek Christian perfection and to do apostolate, endeavouring to sanctify their own professional work; the fact of living immersed in secular reality and respecting its proper autonomy, but dealing with it with the spirit and love of contemplative souls; the primacy which we give in the organization of our apostolate to the individual, to the action of the Spirit upon souls, to the dignity and freedom which derive from the divine filiation of Christians. (Conversations with Monsignor Escrivá, 22)