The dictionary defines the word as one who commits apostasy. That word, in turn, means to revolt, renounce, or abandon a particular way of thinking (Merriam Webster’s, p. 84.). One man, however, defined it: “An apostate is a person who once professed to believe the truth but then turned from it.” He goes on to emphasize the word professed in order to make the following remark: “…no apostate has ever had eternal life abiding in him.” In fact, he was never saved. In the ESV the word apostasy is used twice (Jeremiah 2:19 and Hosea 14:4). In the Jeremiah passage the definition given by Mr. Van Gorder does not stand up to the application as used by the Lord. The context has the Lord saying of Israel that she was devoted and holy (Jeremiah 2:2-3); not exactly words to be used for one “never saved.” In fact, in 2:13 the Lord took note that those to whom He addressed these words had actually forsaken Him. This word is a synonym of the word abandon. To illustrate the practical use of this word, and its real meaning, take note of the use in the following sentence: Mary and John had been married for 23 years, but John abandoned her for another woman. Take the word abandon and replace it with forsake, and the idea is clear. Thus, apostate (apostasy) is not just turning away, but it is turning away from that which had been embraced (cf. Hebrews 13:5).
 Since You Asked, Bible Questions Answered by Paul R. Van Gorder, Radio Bible Class, 1980, p. 7
 Ibid, p. 8