The Old Testament tells the story of King Hezekiah of Judah who received a letter sent by the devil:
And Hezekiah took the letters from the ambassadors; and after he had read them, he went up to the house of the LORD ... and he prayed ... saying, "Jehovah, God of Israel, who dwells among the cherubim, you alone are the God of all the kingdoms of the earth; you made heaven and earth.
Bow your ear, O Lord, and hear; Open your eyes, O LORD, and see; and he hears the words of Sennacherib, who has sent to blaspheme the living God.
2 Kings 19: 14-16
Source
The letter that Hezekiah, king of Judah received, was signed by Sennacherib, king of Assyria; But it was sent directly from hell! The name of Sennacherib means "man of sin"
(or also, "god of the moon multiplying brothers"). It represents Satan, the god of this world, who is determined to create for himself a great brotherhood of haters of God.
At the time that Hezekiah received that satanic letter, Jerusalem was under siege by the powerful Assyrian army. King Sennacherib and his hosts had already led the captivity to the ten tribes of Israel. They fell under the judgment of God because of their immorality, idolatry and apoetasy. People "had sold themselves to do evil," and this was the result:
Because he separated Israel from the house of David ... And the children of Israel walked in all the sins of Jeroboam ... until Jehovah took away Israel from before his face ... and Israel He was taken captive from his land to Assyria.
2 Kings 17: 21-23
In this passage Israel represents the churches of today that have gone astray, that are saturated with sin, prostituted. Israel was full of compromises with the sin of lust, adultery, homosexuality; in short, complete madness for pleasure. And as it happens today, the Israelites had a form of religion devoid of power: '? the king of Assyria brought people from Babylon ... and put them in the cities of Samaria ... not fearing them to Jehovah "(2 Kings 17: 24-25). Among their ranks it was evident that there was an amalgamated gospel, which they carried with them into captivity: "Thus did the people fear the LORD, and at the same time serve their idols" (2 Kings 17:41).
Today the devil has no need to seduce, harangue or write letters to people like that.
It's because he already dominates that part of the Church! Indeed, he has placed his own "angels of light" in the pulpits. He has given them a warm, mixed religion: a sufficient dose of tradition, combined with a great amount of evil.
Today the devil's onslaught remains concentrated on people whose hearts are completely devoted to craving the Lord Jesus. In the account of Hezekiah and Sennacherib, the nation of Judah represents the remnant of the Lord's Church on earth. Is the target of Satan's attacks because he is united in covenant with the Lord and, therefore, represents a tremendous threat to the kingdom of darkness. The Bible says that King Hezekiah of Judah was a godly man:
He did what was right in the eyes of the Lord ... He removed the high places, and broke the images, and cut off the Asherah symbols ... In Jehovah God of Israel he put his hope; neither after him nor before him there was another like him among all the kings of Judah. Because he followed Jehovah, and did not turn away from him, but kept the commandments ... And Jehovah was with him; and wherever he went, he prospered.
2 Kings 18: 3-7
That was the reason why the "man of sin" was determined to destroy Hezekiah. And this is the same reason why Satan is going to attack you.
When man decides to live for God he will always have attacks from the enemy, the goal of satan is to destroy the man of God and of purpose, but God will always be on our side as he was with Hezekiah.
Thanks for sharing @marialara.