heresy in the Bible from dictionary.com
from a Greek word signifying (1) a choice, (2) the opinion chosen, and (3)the sect holding the opinion. In the Acts of the Apostles (5:17; 15:5; 24:5,14; 26:5) it denotes a sect, without reference to its character. Elsewhere,however, in the New Testament it has a different meaning attached to it.Paul ranks "heresies" with crimes and seditions (Gal. 5:20). This word also denotes divisions or schisms in the church (1 Cor. 11:19). In Titus 3:10 a"heretical person" is one who follows his own self-willed "questions," and who is to be avoided. Heresies thus came to signify self-chosen doctrines not emanating from God (2 Pet. 2:1).
1.opinion or doctrine at variance with the orthodox or accepted doctrine, especially of a church or religious system.
2.the maintaining of such an opinion or doctrine.
3.Roman Catholic Church. the willful and persistent rejection of any article of faith by a baptized member of the church.