According the New Testament, the Church is composed of Jesus as the head, and Christians as the body. The head of the Church has a mother, Mary. The mother of the head of the Church is likewise the mother of the body of the Church (i.e., Christians). If someone says otherwise, then such a person is, consequently, denying the union between the head and the body.
Jesus is the only true child of God, and everyone else is a creature. Nevertheless, through the sacrament of Baptism we become brothers and sisters of Christ, and therefore his Father becomes our Father as well. According to the language of the New Testament, we cease being mere creatures and become “adopted” children of our heavenly Father. If the Father of Christ becomes our Father, then the mother of Christ becomes our mother as well.
Because Mary is our mother, she can provide things to us that is in the nature of a mother to provide, such as nurturing, protection, guidance and instruction. Ultimately, her role is to help us know Jesus better. Mary has a two-fold role according to God’s plan of salvation for the world. Her first role was to be the one through whom Christ came into the world. Her second role is to help the world come to know Christ. It is according to this second role that Mary’s spiritual motherhood manifests itself.