"What separates us as believers in Christ is much less than what unites us." (Pope John XXIII) Almost all important doctrine is completely agreed upon between Catholic Christians and other Christians. Here is the joint declaration of justification by Catholics (1999), Lutherans (1999), and Methodists (2006): By grace alone, in faith in Christ's saving work and not because of any merit on our part, we are accepted by God and receive the Holy Spirit, who renews our hearts while equipping us and calling us to good works. http://www.vatican.va/roman_curia/pontifical_councils/chrstuni/documents/rc_pc_chrstuni_doc_31101999_cath-luth-joint-declaration_en.html There are many minor doctrine issues and some major cultural traditional differences which, I believe, do not matter that much. A Catholic worships and follows Christ in the tradition of Catholicism which, among other things, recognizes that Christ made Peter the leader of His new Church and Pope Benedict XVI is Peter's direct successor. For more information, see the Catechism of the Catholic Church: http://www.usccb.org/catechism/text/index.shtml With love in Christ.

1) As far as I can see, they all consider themselves Christians, even if some of them are not considered Christians by the others: "Worldwide, Christians are divided, often along ethnic and linguistic lines, into separate churches and traditions. Technically, divisions between one group and another are defined by doctrine and church authority. Issues such as the nature of Jesus, the authority of apostolic succession, and papal primacy separate one denomination from another. Catholicism is the largest denomination, comprising just over half of Christians worldwide. Protestant denominations comprise about 40% of Christians worldwide, and together the Catholics, Protestants, Anglicans, and closely related denominations compose Western Christianity. Eastern Orthodoxy, largely Greek and Russian, and the much smaller Oriental Orthodoxy are considered Eastern Christianity. Western Christian denominations prevail in Europe and its former colonies. Eastern Christian denominations are represented mostly in Eastern Europe (including all of Russia), and the Near East. Christians have various doctrines about the Church, the body of faithful that they believe was established by Jesus Christ, and how the divine church corresponds to Christian denominations. Together both the Catholics and the Eastern Orthodox consider themselves to faithfully represent the One Holy Catholic and Apostolic Church. Protestants exist, historically, due to several perceived Catholic Church theologies and practices that they consider unorthodox, corrupt or anti-Biblical. Generally, members of the various denominations acknowledge each other as Christians, at least to the extent that they acknowledge historically orthodox views including the deity of Jesus and doctrines of sin and salvation, even though some obstacles hinder full communion between churches. Since the reforms surrounding Vatican II, the Catholic Church has referred to Protestant churches as denominations, while reserving the term "church" for apostolic churches, including the Eastern Orthodox." Source and further information: http://en.wikipedia.org/wiki/Christian_denomination 2) The best would be to look at their specific descriptions, you will find them listed here with many other Christian Churches and links to further information: http://en.wikipedia.org/wiki/List_of_Christian_denominations