Alcuin of York — on Rev 21:8 (QUESTIONS AND ANSWERS MANUAL ON REVELATION)

“THERE FOLLOWS: But the fearful, and unbelieving, and the abominable, etc. ANSWER: He always mixes pleasant words with severe ones to instill carefulness into us. As the Psalmist says, The Lord keepeth all them that love him; but all the wicked he will destroy. [Ps. 144:20] He puts the fearful together with the unbelieving because you are afraid to venture into the battle when you doubt the reward of the winner. THERE FOLLOWS: And all liars, they shall have their portion in the pool burning. ANSWER: He shows that there are many kinds of lies; but the most dangerous and most detestable one is the one with which you sin against religion, this being the kind of lie about which he said earlier, "They say they are Jews, and are not, but do lie, for they are the synagogue of Satan." [Rev. 2:9 and 3:9]”