ICON: Religious painting traditional among many Eastern Christians. Christian iconography expresses in images the same Gospel message that Scripture communicates by words (1160).
ICONOCLASM: A heresy which maintained that veneration of religious images is unlawful. Iconoclasm was condemned as unfaithful to Christian tradition at the Second Ecumenical Council of Nicaea in 787 A.D. (2131).
IDOLATRY: The divinization of a creature in place of God; the substitution of some one (or thing) for God; worshiping a creature (even money, pleasure, or power) instead of the Creator (2112).
IMMACULATE CONCEPTION: The dogma proclaimed in Christian Tradition and defined in 1854, that from the first moment of her conception, Mary–by the singular grace of God and by virtue of the merits of Jesus Christ–was preserved immune from original sin (491).
IMMORTALITY: The quality of the spiritual human soul whereby it survives the death of the body and remains in existence without end, to be reunited with the body at the final resurrection (366).
IMPEDIMENT: An obstacle that makes a person ineligible for performing an act or receiving a sacrament, e.g., Holy Orders or Matrimony (cf. 1635).
INCARNATION: The fact that the Son of God assumed human nature and became man in order to accomplish our salvation in that same human nature. Jesus Christ, the Son of God, the second Person of the Trinity, is both true God and true man, not part God and part man (461, 464).
INCREDULITY: The willful refusal to assent to revealed truth, or even the neglect of this truth (2089).
INDULGENCE: The remission before God of the temporal punishment due to sin whose guilt has already been forgiven. A properly disposed member of the Christian faithful can obtain an indulgence under prescribed conditions through the help of the Church which, as the minister of redemption, dispenses and applies with authority the treasury of the satisfactions of Christ and the saints. An indulgence is partial if it removes part of the temporal punishment due to sin, or plenary if it removes all punishment (1471).
INERRANCY: The attribute of the books of Scripture whereby they faithfully and without error teach that truth which God, for the sake of our salvation, wished to have confided through the Sacred Scriptures (107).
INFALLIBILITY: The gift of the Holy Spirit to the Church whereby the pastors of the Church, the pope and bishops in union with him, can definitively proclaim a doctrine of faith or morals for the belief of the faithful (891). This gift is related to the inability of the whole body of the faithful to err in matters of faith and morals (92).
INITIATION, CHRISTIAN: The foundations of every Christian life laid by the Sacraments of Baptism, Confirmation, and Eucharist. The process by which a non-baptized person is prepared to become a full member of the Church is called the catechumenate, which was restored in the Latin Church by the Second Vatican Council, and whose distinct stages and rites are found in the Rite of Christian Initiation of Adults (1212, 1230).
INSPIRATION: See Biblical Inspiration.
INSTITUTE, RELIGIOUS: A society whose members, in accord with Church law, live a life consecrated to Christ and shared with one another by the public profession of the evangelical counsels of poverty, chastity, and obedience (925). See Consecrated Life.
INSTITUTE, SECULAR: A form of consecrated life in which the Christian faithful living in the world strive for the perfection of charity and work for the sanctification of the world especially from within (928).
INTERCESSION: A form of prayer of petition on behalf of others. The prayer of intercession leads us to pray as Christ, our unique Intercessor, prayed (2634).
INTERCOMMUNION: Participation or sharing in the reception of the Eucharist or Holy Communion by Christians who are not fully united to or in full communion with the Catholic Church (1398).
IRRELIGION: A vice contrary by defect to the virtue of religion. Irreligion directs us away from rendering to God what we as creatures owe him in justice (2095, 2110).
ISRAEL: The Jewish people, chosen by God to be his people and named after Israel (Jacob), from whose twelve sons the tribes of Israel descend. God formed Israel into his priestly people in their exodus from the slavery of Egypt, when he made the first or Old Covenant with them and gave them his Law through Moses (62).