Have you ever noticed how often you here this quoted but the latter part seems to be left out.
Hosea 4:6 My people are destroyed for lack of knowledge: because thou hast rejected knowledge, I will also reject thee, that thou shalt be no priest to me: seeing thou hast forgotten the law of thy God, I will also forget thy children.
It is serious to not be half hearted and carried away about every wind of doctrine, it is the day and hour to be diligent that you not the others make your calling and election sure.