"The beast out of the earth is the religious system that arises out of the soulical nature of man. While we once looked about for a laser-tattooed identification number, or a microchip in the forehead to be the “mark of the beast” — was it not truly there for us to see all along, for John plainly told us, “HERE IS WISDOM. Let him that hath understanding count the number of the beast; for it is the NUMBER OF MAN and HIS NUMBER IS SIX HUNDRED, THREE SCORE AND SIX.” Now, I am aware that the King James Bible says that “it is the number of a man,” but the indefinite article “a” is supplied by the translators and is not necessarily included in the Greek, since that language has no indefinite article. It can quite well be translated without an article at all, as in Psalm 8:4, “What is man (not a man), that thou art mindful of him?” In our text the word for “man” is not Adam, but anthropos, meaning “a human being; humanity; human-kind.” It denotes the human race as against any other species of being. The Concordant New Testament correctly translates it, “for it is the number of mankind.” Anthropos is the word used in II Timothy 3:17 wherein we read, “That the man of God may be perfect, thoroughly furnished unto all good works.” “Man of God” is not referring to a particular man, or one single man, but rather to every man of God. It is a corporate expression denoting a company of men. Likewise, the number of the beast is not referring to one man; it’s every man who possesses a soulical nature capable of spawning religious attitudes, actions, traditions, and systems! Thus we see that the number of the beast that is called the number of a “man” is the number or nature of a “corporate man” or set of men and not one man we are to look for. This “man” is already here and has been here from the dawn of history! He has found a unique expression since Christ birthed His church in the earth, bringing forth in the midst of the Lord’s people another system, a beastly religious system calling itself “the church” and which bears a striking resemblance to the Lamb of God but speaks words which sound like the voice of the dragon!"

Much more in the full study:

https://www.godfire.net/eby/rev-158.html