A Summary of The Catholic Faith

Should one summarize the Christian doctrine, that could be done like follow. The Omnipotent God, who is Trinity -Father, Son and Spirit, reigning over everything, decides, through a plain motion of His own will, to create Man in his image and into his confidence. Due to the Original Sin, man was to cut himself from God's faith. The whole History then turns the History of the relationship between God and Man as it takes place along five instalments

• God, first, repents himself to have created Man as the latter is becoming evil to such a extent (like the story of Abel and Cain, etc.), and He contemplates destroying him through the Flood. God however changes his thoughts and he saves Noah and his family (which is the foundation, through Noah's sons, of the peoples of the Earth). Noah and the Ark is pointing to the beginning of God's will to bring man, against man himself included, back into His trust
• God then turns to the Hebrews among Earth's peoples. Like the 'Chosen People,' they are given by the Father the Tablets of Stone and a general reference to the way how to behave themselves, which either may keep the Hebrews into the faith and the blessings of God, or have them to get distant and be cursed (like, for example, when both the kingdoms of Israel were destroyed and with the Babylonian captivity)
• with one more step into His will that man come back into his trust, God, at that time, sacrifices his Son, Jesus-Christ to the benefit of mankind. That is erasing the consequences of the Original Sin and giving Man, generally, the way to the sacred confidence
• following almost immediately, God comes to strenghten the gift of his Son through the Holy Spirit. God sends his Spirit to guide and guard Man unto the way given by Christ

Thence at last, the history, as Christians are placed under the aegis of the Church, is now unfolding into the world as it will eventually lead to the End of Days, which will constitute the last struggle betwen God and Evil -between keeping into God's confidence or to get distant from it- and to the Last Judgment, which will constitute, as far as it is concerned, the definitive victory of God. Men who will have been saved through, will then, in the New Jerusalem, everlastingly live into the Faith of God

.to a more detailed content of the Roman Catholic Church's doctrine, please check the Catechismo Della Chiesa Cattolica page, at the official Vatican site, whence you will find links to the Catechism of the Church in varied languages. The Compendium below is a summary to the Catechism (caution, that page is in Italian)