Take heed that no man deceive you
Matthew 24:4 And Jesus answered and said unto them, Take heed that no man deceive you. 5 For many shall come in my name, saying, I am Christ; and shall deceive many.
Mark 13:5 And Jesus answering them began to say, Take heed lest any man deceive you: 6 For many shall come in my name, saying, I am Christ; and shall deceive many.
Luke 21:8 And he said, Take heed that ye be not deceived: for many shall come in my name, saying, I am Christ; and the time draweth near: go ye not therefore after them.
I have provided the three references that many are familiar with. Sadly there is a lot of misquoting of this and though many are familiar, few actually read what is said carefully.
1. "For many shall come in my name, saying, I am Christ"
Many Christians erroneously think if someone "comes in the name of Jesus" then they are not a deceiver. That is absurd, the Lord told us all three times they would come in His name. This is what we mean when we say "wolves in sheep's clothing". That is what Paul warned about in Acts. This is what the Judaizers were in Galatians.
Second many assume that saying "I am Christ" is a specific reference to cults like Jim Jones or Charles Manson. Of course, but the word "Christ" means "anointed". John told us that we all have the anointing. There are many Christian leaders that come in the name of Jesus but claim to have a "special anointing". Anyone claiming to have "a special anointing" should be a major red flag. We have all received an anointing, so I am not talking about those who teach on the anointing that we have all received. No, if they refer to this person as "the anointed man of God" that should be a warning. All genuine men of God are anointed. It is unnecessary to add that. It is like someone saying "I'm gonna be completely honest". That should be a major red flag. Why would you say that if you aren't always completely honest.
The time draweth near
2. Many do not realize that only in Luke does it say "the time draweth near". Matthew is written to the Jews, they get saved as a nation at the end of the seven year tribulation. Mark is written to those left behind, they go through the first half of the tribulation. Luke is written to those taken before the tribulation. Matthew and Mark do not need someone telling them "the time is near" because they are already in the time and they know it. The deception will be the antichrist claiming to be the Christ. The term "antichrist" does not mean against or contrary to Christ, it means "in place of Christ". The Antichrist is a counterfeit Christ.
So then let's look at Luke as it is most applicable to today. There are many people saying "the time is near". By itself that is not what the Lord is warning you about. Nor is He warning you that "coming in the name of the Lord" is a red flag. He is simply saying by itself that is not proof they are truly speaking from the Lord Jesus. A counterfeit is similar to the real thing. The real thing comes in the name of the Lord and if the Lord's coming is near they also will be telling you the time is near". No there are two things that will stand out, two witnesses that are special to the false ones. First they claim a special anointing, or their followers claim this person has a special anointing or they way they speak implies they have a special anointing. Second, they are trying to get you to follow them. They sell books, they have a church they want you to join, etc. They have a financial incentive.
So then, I do not subscribe to any site that requires a paywall nor do I buy their books. I have made a few exceptions and I did buy a few videos. To my understanding all genuine followers of the Lord have received freely and so they also are to "freely give". Do not take this concept to the extreme, Paul worked with his hands so that he could give the gospel for free, however, he also taught that the OT says "you shall not muzzle the ox that treads out the corn" as meaning those that work to teach us the Bible should be supported. I am not against buying books, videos, or joining a church. And without a doubt you should tithe as the Lord leads you. God loves a cheerful giver.
This is why there is a warning to us to not be deceived. There is no hard and fast rule that something is wrong other than the life and peace you get from the Holy Spirit. The Lord is not saying that if someone comes in the name of the Lord they are a false prophet, what He is saying is just because someone says they are coming in the name of the Lord don't drop your guard. Likewise He is not saying that if someone sells a book or video they are a false prophet, what He is saying is that all the false prophets have a profit motive. Think of the first circle is all the Lord's sheep, they all come in the name of the Lord but a few "wolves in sheep's clothing will be hiding in the midst". The second circle is all the false prophets have a profit motive, now mixed in there will be a few genuine prophets of the Lord who are also selling books, videos, etc. I don't drop my guard simply because someone says they are coming in the name of the Lord. However, if someone is trying to make money off of their ministry then my antenna is on high alert. Now if someone tries to convince me they have a special anointing I immediately cross them off my list, I'll stick with those that have the same anointing as me. If someone tries to prove to me their ministry is blessed because they have gold chains, luxury cars, a mansion and a private plane then I cross them off my list as well.
But there is a reason why Jesus said that their message will be "the time is near". An evil and adulterous age seeks a sign that the time is near. They have this thought that they can live in the world committing sins right up until the Lord returns, then they jump over to the Lord and as long as they are in church on the day the Lord returns they get raptured. So one person will point out a prophecy or a sign indicating the Lord is near, but their goal is to get closer to the Lord and be faithful to their calling and His command to watch. Someone else will be presenting the signs the Lord is near so that you will jump to his congregation and follow him hoping that will win you salvation. So ask the Lord in prayer, which message is this person speaking?
Go ye not after them
That is how you are deceived. Obviously you can't get to this point without listening to them. The Lord is not saying "don't listen". If that were the case then what is the point of having the gift of discernment or of having the Holy Spirit within you leading and guiding. What the false prophets do is give you just enough to lure you to follow them. With a true prophet they are not trying to lure you anywhere. There is no concluding word to send money somewhere, or to come to some conference or to pay a fee to hear more or buy a video or book.