"4 If anyone says, “I know Him,” but does not keep His commandments, he is a liar, and the truth is not in him. 5 But if anyone keeps His word, the love of God has been truly perfected in him. By this we know that we are in Him:…"
Many will say they believe the Bible but become angry when it is mentioned to prove their actions are in opposition to Him. Anger against God's Word is sin, disobedience to what we know He says is sin.