Ezra’s Adversaries: mentioned in Ezra 4:1, were Samaritans who had blended in   the LORD* with false gods, which would have profaned the Temple that Ezra was called to rebuild. Ezra could not let them work on the Temple, as this article explains.

Ezra 4.1. Now when the adversaries of Judah and Benjamin heard that the children of the captivity were building the Temple to the LORD* God of Israel, 2. then they came to Zerubbabel and to the heads of the families and said to them, Let us build with you, for we seek your God, like you do and we have been sacrificing to Him since the days of Esar-haddon king of Assyria, who brought us up here. 3. But Zerubbabel and Yeshua and the rest of the heads of the families of Israel, said to them, You have nothing to do with us to build a House to our God, but we ourselves together will build to the LORD* God of Israel, as king Cyrus the king of Persia has commanded us.

Israel Carried to Assyria

2 Kings 17:5. Then the king of Assyria came up throughout all the land and went up to Samaria and besieged it three years. 6. In the ninth year of Hoshea, the king of Assyria took Samaria and carried Israel away to Assyria and placed them in Halah and in Habor by the river of Gozan and in the cities of the Medes.

2 Kings 17:7. For so it was that the children of Israel had sinned against the LORD* their God, Who had brought them up out of the land of Egypt, from under the hand of Pharaoh king of Egypt and had revered other gods 8. and walked in the statutes of the nations and of the kings of Israel, which they had made, whom the LORD* cast out from before the children of Israel. 9. And the children of Israel did secretly the things that were not right against the LORD* their God and they built high places for themselves in all their cities, from the tower of the watchmen to the fortified city. 10. And they set up pillars and groves for themselves on every high hill and under every green tree. 11. And there they burned incense in all the high places, as did the nations whom the LORD* carried away before them, and wrought wicked things to provoke the LORD* to anger, 12. and they served idols, of which the LORD* had said to them, You will not do this thing. 13. Yet the LORD* testified against Israel and against Judah, by all the prophets and all the seers saying, Turn from your wicked ways! Keep My commandments and My statutes, according to the entire Torah (Teaching) which I commanded your fathers and which I sent to you by My servants the prophets! 14. However, they would not listen, but hardened their neck, like the neck of their fathers who did not believe in the LORD* their God. 15. And they rejected His statutes and His covenant that He made with their fathers and His testimonies which He testified against them, and they followed vanity and became vain, and went after the nations that were around them, concerning whom the LORD* had charged them, that they should not do like them. 16. And they left all the commandments of the LORD* their God and made molten images for themselves, two calves, and made a grove and worshipped all the host of heaven and served Baal. 17. And they caused their sons and their daughters to pass through the fire and used divination and enchantments, and sold themselves to do bad things in the sight of the LORD*, to provoke Him to anger. 18. Therefore the LORD* was very angry with Israel and removed them out of His sight. There was no one left but only the tribe of Judah. 19. Also Judah did not keep the commandments of the LORD* their God, but walked in the statutes of Israel which they made. 20. And the LORD* rejected all the seed of Israel and afflicted them and delivered them into the hand of looters until He had cast them out of His sight. 21. For He tore Israel from the house of David, and they made Jeroboam the son of Nebat king, and Jeroboam drove Israel from following the LORD* and made them sin a great sin. 22. For the children of Israel walked in all the sins of Jeroboam which he did. They did not depart from them 23. until the LORD* removed Israel out of His sight, as He had said by all His servants the prophets. So Israel was carried away from their own land to Assyria to this day.

2 Kings 17:24. And the king of Assyria brought people from Babylon and from Cuthah and from Ava and from Hamath  and from Sepharvites, and placed them in the cities of Samaria instead of the children of Israel. And they possessed Samaria and lived in its cities. 25. And so it was at the beginning of their dwelling there that they did not revere the LORD*. Therefore the LORD* sent lions among them, which slew some of them. 26. So they spoke to the king of Assyria saying, The nations which you have removed and placed in the cities of Samaria do not know the manner of the God of the land, therefore He has sent lions among them and, behold, they are slaying them because they do not know the manner of the God of the land.

2 Kings 17:27. Then the king of Assyria commanded saying, Carry one of the priests there whom you carried away from there and let them go and live there, and let him teach them the manner of the God of the land.

The priest brought the Torah and the religion of the Hebrews, introducing the LORD* to the new people of Samaria. Those people blended their old religions with the Hebrew, creating a hybrid, a mixture of the Godly with ungodly, they were adversaries of the true worshippers of the LORD*. The same thing happened to those who brought foreign wives to Israel with Ezra and Nehemiah.

Separation from Heathen Wives

Ezra 10.1. Now when Ezra had prayed, and when he had confessed, weeping and casting himself down before the House of God, there assembled to him out of Israel a very great congregation of men and women and children, for the people wept very bitterly. 2. And Shechaniah the son of Jehiel, of the sons of Elam, answered and said to Ezra, We have dealt treacherously against our God and have taken foreign wives of the peoples of the land, yet now there is hope in Israel concerning this thing. 3. Now therefore let us make a covenant with our God to put away all the wives and such as are born of them, according to the counsel of my Lord and of those who tremble at the commandment of our God and let it be done according the Torah (Teaching). 4. Arise, for this matter is for you, we also will be with you. Be of good courage and do it.

Those wives had not converted to Judaism, but blended Judaism with their false gods, bringing unbelief and unfaithfulness to the restored Temple and Jerusalem. Thus, Ezra was required to order them to be separated.

This blending of Godly and ungodly is seen today in the 21st century, with a blend of Christianity and Islam, called Chrislam being promoted, and blends of Christianity with eastern religions, Hindu and Buddhist among them being promoted. The Judeo-Christian God, the God of Abraham, Isaac, and Jacob is not to be diluted, profaned, with any false gods, at any time, forever.