Why does Catholicism believe that there is no salvation outside of the church? The theif who died next to Christ (Like 23) was promised salvation by Christ and he had no affiliation with the church. He recieved no sacraments, he never recognized the Pope, and he did no good works. All he had was faith... isn't his salvation uncongruent with current Catholic doctrine?
Jesus instituted the Church... that is the Church came about after the Apostles came to understand what Jesus was preparing them for, when he told Peter, "You are rock, and upon this rock I will build my church, and the jaws of death shall not prevail against it."
After Penticost, with the descent of the Holy Spirit, the Church began to take shape. Jesus was not bound by the teachings of the church, because He preexisted the church. Jesus, as head of the Church, has and had, the right to forgive anyone He wanted to, and wants to.
The Church teaches, that the Catholic Church has the fulness of truth. Other Christian Churches have partial truth, so even though people of other Churches can and are saved, it is only through the graces, that originate through the Catholic Church. This can be more easily understood when you realize that all Christian Religions are rooted in the Catholic Church, and that at some point and time, they branched from the Catholic Church.