Because there arose no little dissension and debate
by Paul and Barnabas with them,
it was decided that Paul, Barnabas, and some of the others
should go up to Jerusalem to the Apostles and presbyters
about this question.
There are many points which the Church leaves to the discussion of theologians, in that there is no absolute certainty about them. As the eminent cardinal Newman remarked, such controversies do not disrupt the Church’s unity; rather they contribute greatly to a deeper and better understanding of her dogmas. These very differences shed in effect a new light on the Church’s teaching, and pave and fortify the way to the attainment of unity.
Catechism of the Catholic Church
From the beginning, this one Church has been marked by a great diversity which comes from both the variety of God’s gifts and the diversity of those who receive them. Within the unity of the People of God, a multiplicity of peoples and cultures is gathered together. Among the Church’s members, there are different gifts, offices, conditions, and ways of life. “Holding a rightful place in the communion of the Church there are also particular Churches that retain their own traditions.” The great richness of such diversity is not opposed to the Church’s unity. Yet sin and the burden of its consequences constantly threaten the gift of unity. And so the Apostle has to exhort Christians to “maintain the unity of the Spirit in the bond of peace.”
In fact, “in this one and only Church of God from its very beginnings there arose certain rifts, which the Apostle strongly censures as damnable. But in subsequent centuries much more serious dissensions appeared and large communities became separated from full communion with the Catholic Church – for which, often enough, men of both sides were to blame.”…
“However, one cannot charge with the sin of the separation those who at present are born into these communities [that resulted from such separation] and in them are brought up in the faith of Christ, and the Catholic Church accepts them with respect and affection as brothers.… All who have been justified by faith in Baptism are incorporated into Christ; they therefore have a right to be called Christians, and with good reason are accepted as brothers in the Lord by the children of the Catholic Church.”….
The desire to recover the unity of all Christians is a gift of Christ and a call of the Holy Spirit. Certain things are required in order to respond adequately to this call: