See the Compendium of the Catechism of the Catholic Church condensed into 140 character summaries! Follow me on Twitter and watch for #C4 tweets.
What follows is Part 1, Section 1 of the Compendium (nn. 1-32; cf. Catechism nn. 1-182). Please excuse the crude abbreviations; I only use them to meet the 140 character limit of Twitter!
#C4 1. God cre8d man out of love 4 man 2 share in His life. God sent His Son Jesus 2 b r Savior from sin & make us God's adopted children.
#C4 2. Man desires God b/c we r made in His image. even if we ignore this desire, God continues to call man to commmunion with Him.
#C4 3. Man can, by natural reason alone, know God as the origin & end of the universe, as the highest good & as infinite truth & beauty.
#C4 4. Natural reason alone is insufficient 2 grasp the MYSTERY of God, though. This is why man is in need of God's REVELATION.
#C4 5. Man & all creation reflects (poorly) God's infinite perfection. Our language can never fully xpress God's mystery, but we must try.
#C4 6. God, in goodness & wisdom, reveals Himself 2 man: His saving plan of love centered in Christ, in whom we r 2 b God's adopted sons.
#C4 7. God 1st revealed Himself 2 Adam & Eve, r first parents, inviting them 2 communion w/ Him. After the Fall, God continued w/ Noah.
#C4 8. Next God called Abram, Isaac & Jacob (Israel). God took Israel, His chosen people, out of slavery & made them a kingdom.
#C4 9. God's full revelation IS His Son, the Word-made-flesh, Jesus Christ. In Jesus & the Holy Spirit, revelation is complete.
#C4 10. Priv8 revelation is helpful only if it leads one to Christ. Priv8 revelation can't surpass/change Christ's public revelation.
#C4 11. God wants all men to know Jesus & b saved, so Christ commanded His disciples to teach all nations, transmitting God's revelation.
#C4 12. This is "Apostolic Tradition", by which Christ's message is handed on, in the Holy Spirit, via Scripture, preaching, worship, etc.
#C4 13. Apostolic Tradition is found in Sacred Tradition (living transmission of God's word) & Sacred Scripture (revelation in writing).
#C4 14. Sacred Tradition & Sacred Scripture are united. Each flows from the same divine source. Both make up the one deposit of faith.
#C4 15. The deposit of faith was entrusted by the Apostles to the whole Church which, guided by the Holy Spirit, receives and lives it.
#C4 16. The Magisterium (Bishops) of the Church has the task of authentically interpreting the deposit of faith.
#C4 17. Scripture Tradition & Magisterium r so united that one can't stand w/o the others. Each operates in the Holy Spirit to save souls.
#C4 18. Scripture teaches the truth because God is its author, Who inspired men to write it. Scripture is inspired and is w/o error.
#C4 19. Scripture must b read 1) as a whole, 2) w/in the Church's tradition, and 3) respecting the harmony of the truths of the faith.
#C4 20. The "canon" of Scripture is those books received through Apostolic Tradition by the Church as inspired: 46 OT books & 23 NT books.
#C4 21. Christians respect the Old Testament b/c it's truly God's word, attests to His saving love, and prepares for the coming of Christ.
#C4 22. The New Testament conveys the ultimate truth of divine revelation. The 4 Gospels r the main witnesses 2 Christ's life & teachings.
#C4 23. Scripture (OT & NT) is one because God's Word is one, His saving plan is one. The OT prepares for the NT; the NT fulfills the OT.
#C4 24. Scripture gives support to the Church's life. It confirms faith & feeds the soul. God's word is a lamp 4 r feet & a light 4 r path.
#C4 25. Man, by divine grace, responds 2 God's revelation w/ obedience of faith: surrendering ourselves to God & accepting His truth.
#C4 26. Abraham and the Blessed Virgin Mary are prime witnesses to "obedience of faith" in the Scriptures: "let it b according 2 your word."
#C4 27. Believing in God (Father, Son, Holy Spirit) means entrusting yourself 2 Him & assenting 2 all the truths He reveals b/c He IS Truth.
#C4 28. Faith: supernatural virtue REQUIRED 4 salvation; free gift from God; a human act; works thru LOVE; keeps growing; taste of Heaven.
#C4 29. Faith is above reason, but doesn't contradict science b/c both come from God. God gives us the light both of reason & of faith.
#C4 30. Faith is a PERSONAL act, but also an ECCLESIAL act of the whole Church: we believe IN and BY the Church, our teacher & mother.
#C4 31. Formulas of faith are important b/c they express, celebrate, & share the truths of the faith w/ others through a common language.
#C4 32. The Church has ONE faith, despite diversity of languages, cultures, and rites, b/c of the ONE Lord Who revealed it.