Allow an often-used quote that is never understood:

“‘I know your tribulation and your poverty (but you are rich) and the slander of those who say that they are Jews and are not but are a synagogue of Satan." Revelation 2:9

This same language is used again in the next chapter:

"Behold, I will make those of the synagogue of Satan who say that they are Jews and are not, but lie—behold, I will make them come and bow down before your feet, and they will learn that I have loved you." Revelation 3:9

Here's a quick lesson on the context of these two passages, which are bookends within the letters to the seven churches of Asia. These letters of Revelation are a microcosm of Our Savior's telling of the church age, from the first century until today.

The first church, Ephesus, spells out the characteristics of the New Testament church in the first century. At the close of the first century, the curtain drops, and when it rises again, we see a completely different church compared to the Apostolic Church, where the Apostles began on the Day of Pentecost. We see a church very much compromised... But compromised by who?

In the second church era, Smyrna, a very persecuted assembly of Believers, knew who... They say they are Jews but are not and do lie... That's who.

This pattern continued throughout the church age and is prevalent today. As the church age began to draw to its end in 1934, the Philadelphia church began, and we see the other bookend identified once again—the so-called Jews holding geopolitical sway over anything righteous in the New World.

These Jews are the same entity to which Yeshua spoke directly in John chapter 8:44, the literal sons of Satan.

"You are of your father the devil, and your will is to do your father’s desires. He was a murderer from the beginning and does not stand in the truth because there is no truth in him. When he lies, he speaks out of his own character, for he is a liar and the father of lies." John 8:44

In this chapter, Yeshua very clearly identifies these men as Edomites. Note The following exchange:

The Jews - "They answered him, “We are offspring of Abraham and have never been enslaved to anyone. How do you say, ‘You will become free’?” Verse 33.

Yeshua - "I know that you are offspring of Abraham; yet you seek to kill me because my word finds no place in you." verse 37

Thus, Yeshua very clearly defines who He is speaking with. History is very clear. The only seedline of Abraham who has never been in captivity to anyone is the descendants of Esau, now called Edom.

Moreover, Cain's seedline is tied directly to Esau via Yeshua's words, "He was a murderer from the beginning." Yeshua's words give this fact a second witness. Notice this text:

"Therefore also the Wisdom of God said, ‘I will send them prophets and apostles, some of whom they will kill and persecute,’ so that the blood of all the prophets, shed from the foundation of the world, maybe charged against this generation, FROM THE BLOOD OF RIGHTEOUS ABEL to the blood of Zechariah, who perished between the altar and the sanctuary. Yes, I tell you, it will be required of this generation." Luke 11:49-51

Again, the context is clear. Yeshua is speaking directly to The Jews of His day.

Conclusion: Cain killed Abel. The Jews of Yeshua's day are the sons of Satan. Cain is their progenitor father, and thus, Cain was fathered by Satan as well. This two-seedline war between the righteous bloodline of Adam and the seedline of Satan (see Genesis 3:16; yes, Satan has actual children) is the underlying theme of all of scripture. Esau just married into this evil line.

This is the kind of evil @StewPeters is shedding light upon.