The Catholic Church does no alter the Bible
The Catholic Church is the oldest Christian denomination, therefore progenitor of the Holy Bible. After the Ascension of Jesus Christ and coming of Holy Spirit, the followers of Jesus were very busy following the injunction of their master to preach to the ends of the world. His followers thought that there was little time to spread the good news probably, they were constantly reminded that Jesus promised to take them to where he would be. There was no complete bible until later when Saint Paul admonished them to live and die for Christ alike, meaning that they can record happenings while waiting for Jesus. This is alongside a compilation of the epistles written by apostles especially thirteen letters of Saint Paul.
Another thing worthy of mention is that early Christians were using Old Testament to pray, preach, and reveal fulfillment of revelations. There were two main Tanakh, first is used by the home Jews and other Greek-speaking Jews. Early Christians saw no alteration of Bible only that Tanakh for the Greek-speaking jews contained extra seven books called deuterocanonical books. It is believed that first Christians composed Septuagint Bible has seventy books including the deuterocanonical books; 39 books of Old Testament, 7 deuterocanonicals, and 27 books of New Testament. Protestant churches believe that seven deuterocanonicals were composed by Catholics to suit their doctrines. This usage could be that Greek language was more popular for gentiles than Hebrew, it was quite easier to use it.
It is believed that Saint Paul used them in their letters. Beyond that, Catholic Church believes that faith is rooted in the Bible and the tradition of the apostles as there was no other church when Bible was compiled. This set of christian hold that not everything is written in the Bible, John 21, validate Didache plus other works of tradition. They believe that interpretation of the Bible rests with magisterium who is a highly esteemed group of theologians wholly made up of clergy whose work is to study the Bible within the spirit of the church, so that revelations embedded in the gospel will be clearer. It is their role to make sure that no Bible reference is quoted out of context.
Many of faith which Catholics hold firm but rejected by Protestants are as follows. Mariology is a branch of theology specifically for study of Marian’s role in the history of man’s salvation and her rewards. For other Christian denominations, Mary was just an instrument used by God to achieve his aim for me. He would have used another person other than Mary. For Catholics, it is quite different for Mary was predestined and fortified with graces to carry out the salvific work by giving birth to God, Luke 1:26-38.
Catholic Eschatology included presence of purgatory, interceding for the dead as articles of belief. Protestants are irritated by this seeming fallacy which does not only deceive the adherents but denies absolute truth. With deeper understanding, Catholics believe that God is merciful to purge them of remitted sins that he would accept them into his bosom. This principle stems from the fact no impure thing can enter the kingdom of God; man must pay for all his sins, Apoc 21. You would say that the blood of Christ has paid for all our sins.
A catholic believes that but believes that expiation for sin is quite different from punishment due to sins, 2 Maccabees 12. It goes as far as introducing Indulgence to church. Indulgence as belief is remission of punishment meted out due to sins they committed which have been forgiven, John 20. This forced Martin Luther to leave the church as the presiding Pope asked Christians to pay for building of a church in exchange for indulgence. He further removed Saint James’s epistles due to its discourse on faith and good works.
The sacrament of penance for catholic stems from injunction and power from the injunction given to the apostles to forgive sins Matthew 18. Protestants agree that once you pray to God, he will forgive your sins. Though this is incomplete true, it brings up concept of venial and mortal sins which specify degree of grievances against God. Catholics know that there are sins that cannot be easily forgiven of their gravity. You can compare sin of fornication which tampers with your purity, fidelity and self-control with plucking an orange from my orchard. All Christians use the holy bible but the way its teachings are taught is what makes the difference in the christendom.