Q. 1. The Catholic Church teaches that it is the "Mother Church" to the Protestant churches. It is not a "sister church" to them as some protestant claim. If the Catholic Church is a "Mother Church", how can we children of the "Mother Church" be brothers and sisters to the separated children of the protestant churches that are not sister churches?
The children of the "Mother Church" and those of the "sister churches" cannot be brothers and sisters to each other if their churches are not equal. As children of the "Mother Church", these brothers and sisters in Christ, members of the Church, are the "Mother Church."
A. 1. When the Catholic Church refers to Catholics and protestants as brothers and sisters in Christ, it is a reference to their union in the baptism in Christ. This is confirmed in the Catechism of the Catholic Church were it states:
818 "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."
While Christians are considered brothers and sisters in Christ in accordance with the teachings of the Catechism, our protestant separated friends lack some of the graces granted by God to us in the Sacraments of the Catholic Church. Accordingly, they are imperfect brothers and sisters in Christ. This truth is recognized in their beliefs. They maintain that they are saved by the Bible and faith alone. They reject the Real Presence of Christ in the Holy Eucharist, viewing their participation in the Eucharist as a symbol. Protestant lack the Sacrament of Confession that sanctifies the souls. The Sacraments are required to enjoy the fullness of the Sacramental life.
Because of the aforementioned shortfall, our separated brothers and sisters in Christ cannot claim to be children of a church that is a sister church of the One, Holy, Catholic and Apostolic Mother Church.