Deception

Rev 12:9 - And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him 

Satan deceives the whole world to one degree or another and I am sure that includes me.

1 Kings 22:22: And the LORD said unto him, Wherewith? And he said, I will go forth, and I will be a lying spirit in the mouth of all his prophets. And he said, Thou shalt persuade him, and prevail also: go forth, and do so. Now therefore, behold, the LORD hath put a lying spirit in the mouth of all these thy prophets, and the LORD hath spoken evil concerning thee.

God does deceive people who refuse to listen to him.

Ezekiel 14:9: And if the prophet be deceived when he hath spoken a thing, I the LORD have deceived that prophet, and I will stretch out my hand upon him, and will destroy him from the midst of my people Israel.

Could all preachers who preach pre trib rapture as a FACT be called  false prophets?

I do not mind someone teaching pre trib as long as they say it is a theory and they MUST also teach post trib and tell people to read for themselves and make up their own minds per the Holy Spirit of truth.

2 Thess 2:10-12:  And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved. And for this cause God shall send them strong delusion, that they should believe a lie: That they all might be damned who believed not the truth, but had pleasure in unrighteousness.

There are a whole bunch of "church people" who live in unrighteouness like the world.
People too lazy watching TV to read the Bible can and shall be deceived

2 Ti 3:13: But evil men and seducers shall wax worse and worse, deceiving, and being deceived.