The worldly meaning of deceive:
(of a person) cause (someone) to believe something that is not true, in order to gain personal advantage
3 As Jesus was sitting on the Mount of Olives, the disciples came to him privately. “Tell us,” they said, “when will this happen, and what will be the sign of your coming and of the end of the age?”
4 Jesus answered: “Watch out that no one deceives you.
James 1:22 But be doers of the word, and not hearers only, DECEIVING YOURSELVES.
To be deceived truly, by God’s standards or by His Truth, is to hear what God says for you to do and not do it. This is the real deception. This fulfills what’s happening now (2Thess. 2:1-12). Lawlessness has already been at work and God IS revealing the body of the Lawless One (or ones in that group). Have you heard God say things to you, that you’ve avoided doing? That is lawlessness. Do not be deceived…in other words, don’t hear God speak to you and not do. God will not be mocked. The term ‘mocked’ in Hebrew contexts means: laughter (in merriment or DEFIANCE); derision (disbelief). God will not be laughed at in your unbelief (Ps. 37:13). Remember, if God has told you to do something, it is good and perfect in His eyes, and it does not bring forth uncertainty or unbelief towards Him; it confirms Himself to you instead. That’s the purpose of hearing AND doing.
Don’t get me wrong, many will come claiming His name and deceiving many or basically encouraging disobedience to the leading of the Holy Spirit because they do not do it themselves (Matt. 23:13). But don’t do as they do. Because like in the beginning, Eve did encourage the disobedience, but Adam followed through in not doing what God told him, and he was held accountable too.
The great deception is NOT DOING WHAT GOD SAYS for you to do.