88 We address suppliant prayers to our gracious God, the giver of heavenly light and of all good things, that He safeguard the unity of the Church and extend the fold and kingdom of Christ. We urge all Our brethren in Christ and Our beloved sons to pray fervently for the same intentions. The outcome of the approaching Ecumenical Council will depend more on a crusade of fervent prayer than on human effort and diligent application. And so with loving heart We also invite to this crusade all who are not of this fold but reverence and worship God and strive in good faith to obey His commands.
Source: Ad Petri Cathedram (Vatican.va)