Through Him then, let us continually offer up a sacrifice of praise to God, that is, the fruit of lips that give thanks to His name.
Their preaching work is not approved by God anyway, because acording to WT original teachings their "lips are not clean" and their "sacrifice of praise" is not being received.
Let no one in any way deceive you, for it will not come unless the apostasy comes first, and the man of lawlessness is revealed, the son of destruction, who
opposes and exalts himself above every so-called god or object of
worship, so that he takes his seat in the temple of God, displaying
himself as being God. Do you not remember that while I was still with you, I was telling you these things? And you know what restrains him now, so that in his time he will be revealed. For the mystery of lawlessness is already at work; only he who now restrains will do so until he is taken out of the way. Then
that lawless one will be revealed whom the Lord will slay with the
breath of His mouth and bring to an end by the appearance of His coming; that is, the one whose coming is in accord with the activity of Satan, with all power and signs and false wonders, and
with all the deception of wickedness for those who perish, because they
did not receive the love of the truth so as to be saved. For this reason God will send upon them a deluding influence so that they will believe what is false, in order that they all may be judged who did not believe the truth, but took pleasure in wickedness.