Up until the Second Vatican Council, the Church consistently taught that unity can only come about not when different sects put aside doctrinal questions but when non-Catholics give up their erroneous ideas and embrace the one true faith.
It was necessary that this Church should last for all ages, and that She should traverse the earth in such wise that Her name and mission might be known to all nations; in a word, She was to be Catholic, that is, universal, taking in all times and all places.
To attain eternal life, the virtues bestowed upon Christians by the Holy Spirit must be nurtured within the true Church, under the guidance of legitimate pastors.