Actually, the problem starts with those who call Jesus Christ a liar by denying that Christ meant what he said about His body and His blood.
You know, the sort of people who mock the Eucharist and pretend they're Christian in spite of clearly calling Jesus Christ Himself a liar. Such folks may claim to be Christian but they feel free to call Jesus Christ a liar because they really worship their own, Most High and Holy Self.
You can pick them out in any crowd, though, because like the evil they listen to they hate the body and blood of Christ since they know it's what has defeated them. They're also always afraid of Christ crucified because they know His Crucifixion is our salvation and their sentence to Hell along with their master. That's why they act like a Hollywood B movie Vampire when they see a Crucifix, they do not follow Scripture and preach Christ and Him crucified. Instead, they preach, "me and Jesus are fishin' buddies and since I said the majick words good Ol' Jesus owes me so I can do no wrong".
Jude 1:10 But these men blaspheme whatever things they know not: and what things soever they naturally know, like dumb beasts, in these they are corrupted.
Jude 1:11 Woe unto them! For they have gone in the way of Cain: and after the error of Balaam they have for reward poured out themselves and have perished in the contradiction of Core.
The Church teaches us that we're to avoid the sort of folks who call Christ a liar and leave them to the Holy Spirit to deal with. The reason the Church teaches that is because it's what the Scriptures says to do and like everything else the Church teaches it is the same thing Christ and the Apostles taught. Too bad for the pretend Christians who instead follow their own fantasies and preferences rather than the Word of God.
Titus 3:9 but avoid foolish questions, and genealogies, and contentions, and strivings about the law. For they are unprofitable and vain.
Titus 3:10 A man that is a heretic, after the first and second admonition, avoid: Titus 3:11 Knowing that he, that is such an one, is subverted, and sinneth, being condemned by his own judgment.
Those who continue to deny the deity of Christ by calling Jesus Christ a liar can fool themselves however they like, but they should get used to the idea of hearing, "I never knew you" from the very Jesus Christ they deny is God.