Because the Catholic Church's beliefs are founded on the
revelation of Jesus Christ and the Holy Spirit to the Apostles. The
protestant beliefs are founded on the private wishes of individuals
who lived sixteen centuries later on what they wish was true and
their individual reading of flawed translations of the Sacred
Scriptures.
Catholics teach that the Christian must rely on faith plus
"meritorious works" in order to be saved. Essential to the Roman
Catholic doctrine of salvation are the Seven Sacraments, which are
baptism, confirmation, the Eucharist, penance, anointing of the
sick, holy orders, and matrimony. Protestants believe that, on the
basis of faith in Christ alone, believers are justified by God, as
all their sins are paid for by Christ on the cross and His
righteousness is imputed to them. Catholics, on the other hand,
believe that Christ's righteousness is imparted to the believer by
"grace through faith," but in itself is not sufficient to justify
the believer. The believer must supplement the righteousness of
Christ imparted to him with meritorious works.