From: About.com- Roman Catholic Church- Beliefs and Practices

he Roman Catholic and Orthodox churches were the only established churches prior to all other Christian denominations. For comparison purposes, we will look at the main differences between the beliefs and practices of the Roman Catholic faith and most other Protestant denominations:

• Authority Within the Church - Catholics believe the authority of the church lies within the hierarchy of the church; Protestants believe the authority of the church lies within the believer.
• Baptism - Catholics (as well as Lutherans, Episcopalians/Anglicans and some other Protestants) believe that Baptism is a sacrament that regenerates and justifies, and is usually done in infancy; Most Protestants believe Baptism is an outward testimony of a prior inward regeneration, usually done after a person confesses Jesus as Savior and obtains an understanding of the significance of Baptism. Visit About.com's Catholicism site to understand more about the Catholic Sacrament of Baptism.
• The Bible - Catholics believe that truth is found in the Bible, as interpreted by the church, but also found in church tradition. Protestants believe that truth is found in Scripture, as interpreted by the individual, and that the original writings of the authors of the Bible are without error.
• Books of the Bible - The Catholic Church includes the same 66 books of the Bible as do Protestants, as well as the books of the Apocrypha. Protestants accept only the 66 books of the Old and New Testament.
• Clergy Selection - The Roman Catholic Church appoints all male, and almost all unmarried clergy. Protestants elect mostly male, single or married clergy.
• Forgiveness of Sin - Catholics believe forgiveness of sin is achieved through church ritual, with the assistance of a priest in confession. Protestants believe forgiveness of sin is received through repentance and confession to God directly without any human intercessor.
• Hell - The New Advent Catholic Encyclopedia defines hell in the strict sense, as "the place of punishment for the damned" including limbo of infants, limbo of the Fathers, and purgatory. Similarly, Protestants believe hell is a real physical place of punishment which lasts for all eternity, but reject the concepts of limbo and purgatory.
• • Immaculate Conception of Mary - Roman Catholics are required to believe that whenMary herself was conceived, she was without original sin. Protestants deny this claim.
  • Infallibility of the Pope - This is a required belief of the Catholic Church in matters of religious doctrine. Protestants deny this belief.
  • The Lord's Supper (Eucharist/Communion) - Catholics believe this sacrifice is Christ's body and blood physically present and consumed by believers ("transubstantiation"). Most Protestants believe this observance is a meal in memory of Christ's sacrificed body and blood, and it symbolizes only His life now present in the believer. They reject the concept of transubstantiation.
  • Mary's Status - Catholics believe the Virgin Mary is below Jesus but above that of the saints. Protestants believe Mary, though blessed, is just like all other believers.
  • Prayer - Catholics believe in praying to God and also praying to Mary or a saint to intercede on their behalf. Protestants believe prayer is addressed to God and not to saints.
  • Purgatory - Catholics believe purgatory is a state of being after death in which souls are cleansed by purifying punishments before they can enter heaven. Protestants deny the existence of Purgatory.
  • Right to Life - The Roman Catholic Church teaches that ending the life of a pre-embryo, embryo or fetus cannot be allowed, except in very rare cases where a life-saving operation on the woman results in the unintended death of the embryo or fetus. Individual Roman Catholics often take a position that is more liberal than the official stance of the Church. Conservative Protestants differ in their stance on abortion access. Some permit it in cases where the pregnancy was initiated through rape or incest. At the other extreme, some believe that abortion is never warranted, even to save the life of the woman.
  • Sacraments - Catholics believe the sacraments are a means of grace. Protestants believe they are a symbol of grace.
  • Saints - Much emphasis is placed on the saints in the Catholic religion. Protestants believe that all born again believers are saints and that no special emphasis should be given to them.
  • Salvation - The Catholic religion teaches that salvation depends on faith, works and sacraments. Protestant religions teach that salvation depends on faith only.
  • Salvation (Losing Salvation) - Catholics believe that salvation is lost when a responsible person commits a mortal sin. It can be regained through repentance and the sacrament of confession. Protestants usually believe, once a person is saved, they cannot lose their salvation. Some denominations teach that a person can lose their salvation.
  • Statues - Catholics give honor to statues and images as symbolic of the individual saints. Many Protestants consider veneration of statues to be idolatry.
  • Visibility of the Church - The Catholic Church recognizes the hierarchy of the church, including the laity as the "Spotless Bride of Christ." Protestants recognize the invisible fellowship of all saved individuals. Only God knows the exact makeup of the church.