‘And all the churches will know that I am the one who searches the reins and hearts, and I will give to each of you in accordance with your works. But to you I say, to the rest of you in Thyatira, as many as do not hold this teaching, who do not know the deep things of Satan as they say, I throw on you no other burden. However, that which you have, hold fast until I come.'
For searching the reins and the hearts, searching out what controls men and how they feel and think, see Psalms 7:9; Psalms 26:2; Jeremiah 20:12 where it is the work of God and compare Romans 8:27. Thus the Son of Man is the One Who tests men's motives and thoughts to their very depths, for in the end the final test of any man is the way he lives. In Revelation, as in Jesus' teaching (John 6:29), works include the work of faith, but that faith must reveal itself in action. As James said, ‘faith without works is itself a dead faith' (James 2:17).
The great tribulation that these heretics would face will be witnessed by the churches for ‘all the churches will know ---'. This again confirms that the churches are present throughout Revelation. In Heaven there is only one ‘church', but they are never even described as that (but compare Hebrews 12:23).
The Son of God reserves His specific condemnation for those who commit the evil and hold the evil teaching. On the remainder He wishes to place no further burden than they already have, and He has already commended them. This ‘burden' may have Acts 15:28-29 in mind for its phraseology is echoed in this passage. ‘For it seemed good to the Holy Spirit and to us to lay on you no greater burden than these necessary things, that you abstain from things sacrificed to idols, and from blood, and from things strangled, and from sexual immorality'. Thus Jesus is confirming that Christians are released from Old Testament ordinances including circumcision.
‘Who do not know the deep things of Satan as they say.' This is probably just a reference to the fact that the origin of this teaching is really Satanic although the teachers claim to ‘know the deep things of God' (this is most likely. John applies ‘Satanic' to the Jewish synagogue and to the Roman authorities, and there it was metaphorical also), but it may even suggest that those condemned actually claim to ‘a knowledge of the deep things of Satan' and boast about the fact (contrast here the real ‘deep things of God' (1 Corinthians 2:10).)
However Satan's throne was in Pergamum (Revelation 2:13), and that almost certainly refers to the Temple of Roma and the Emperor there. So these ‘deep things of Satan' may have been connected with the this cult which included open partaking of offerings made to Roma (Rome) and the Emperor, and sexually immoral activities in their love-feasts, with ‘Jezebel' justifying connection with it by false prophesy and even falser teaching. We must beware of syncretists who seek to combine Christianity with lesser religions. The fourth century would see such syncretism under Constantine the Great which would lead to many errors in the church.
Emperor worship was not yet fully established but it was certainly prevalent, especially in the East away from Rome, where the frailties of the Emperors were less well known. We shall see later that the writer speaks harshly of the worship sought, and at times demanded, by Rome, for itself and its Emperors (e.g. chapter 13 on). So ‘Jezebel' and her ilk may well have been tied up with this worship and its consequences, somehow incorporating it into their professed worship of Christ.