Chris·ti·an·i·ty (kr?s?ch?-?n??-t?, kr?s?t?-)n.1. A religion based on the life and teachings of Jesus. Most forms of Christianity hold that Jesus is the son of God and is the second person of the Trinity, through whom humans may attain redemption from sin.2. Christians as a group; Christendom.3. The state or fact of being a Christian.4. pl. Chris·ti·an·i·ties A particular form or sect of the Christian religion: the Christianities of antiquity.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.Christianity (?kr?st??æn?t?) n1. (Theology) the Christian religion2. (Theology) Christian beliefs, practices, or attitudes3. (Theology) a less common word for Christendom1Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014Chris?ti?an?i?ty (?kr?s t?i?æn ? ti) n. 1. the Christian religion, including the Catholic, Protestant, and Eastern Orthodox churches. 2. Christian beliefs or practices; Christian quality or character. 3. the state of being a Christian. 4. Christendom. [1250?1300; Middle English