I believe Christians may “depart from the faith,” “fall away from grace,” even “deny the Lord that bought them” (1Tim. 4:1; Gal. 5:4; 2Pet. 2:1) for the scriptures clearly teach this.
1 Jn 2:19 says: “They went out from us, but they were not really of us; for if they had been of us, they would have remained with us; but they went out, so that it would be shown that they all are not of us.” Those who believe this applies to all who backslide…