We read in Daniel 11:32, that those who are influenced by the spirit of the Antichrist will use smooth words (flattery) to draw people to themselves. The one unmistakable characteristic of every false prophet in history has been flattery. And the one unmistakable characteristic of every true prophet has been rebuke.
False prophets flatter people in order to win them to their group, or to build their own kingdoms, or to get honour, or to get money, etc., Many of these false prophets correspond faithfully with people, in order to retain their personal hold over them. Their letters will not however contain words of rebuke and correction (as in the letters of the Lord and of the apostles - as we read in Revelation 2 and 3 and the epistles). Instead, they will only contain words of flattery commendation.
Smooth words will only defile your heart with pride and self-satisfaction. Words of rebuke on the other hand will cleanse your heart and make it pure. Jesus said "Those whom I love, I reprove and I discipline" (Rev.3:19). Rebuke is one mark of Divine love.
When God sends a prophet into our midst, to rebuke us, that is a proof of the fact that God loves us. When God forsakes a church, it will "no longer have a prophet in its midst" (Psa.74:1,9) to rebuke it. Instead, it will have preachers who preach smooth words (2 Tim.4:3,4). That is a sad condition for any of God's people to be in.
In Revelation 2 and 3, we see that even though five of the seven churches there were in a bad shape, yet the Lord had not forsaken them as yet. The proof of this is seen in the fact that He sent a prophet (John the apostle) to rebuke and correct them through his letters.
John had strong words even for the elders - words such as, "You have left your first love....You are spiritually dead....You are wretched and poor and blind and naked". If those elders and those churches did not respond to those words of rebuke, and repent, they would be forsaken.
Once the Lord "takes away the lamp stand" (Rev.2:5), He will not send His prophets to rebuke that church any more. The false prophets will then take over, and smooth words will be heard regularly at the meetings, Sunday after Sunday!! This has happened in church after church, in generation after generation, throughout these twenty centuries. And it is happening all around us today.