What does it mean to backslide?

The term “backslide” is really an Old Testament concept related to being under the Law. It implies you were climbing, making progress, then your strength failed, and you slipped and started to slide back. Jeremiah 3:6 (KJV) says: “The Lord said also unto me in the days of Josiah the king, ‘Hast thou seen that which backsliding Israel hath done?’” In Jeremiah 8:5 (KJV), it appears as well: “Why then is this people of Jerusalem slidden back by a perpetual backsliding? They hold fast deceit; they refuse to return” (Jeremiah. 8:5). Finally, Proverbs says: “The backslider in heart shall be filled with his own ways” (Proverbs 14:14).