Ezekiel 14:8
And I will set my face against that man, and will make him a sign and a proverb, and I will cut him off from the midst of my people; and ye shall know that I am the LORD. And I will set my face against that man, and will make him a sign and a proverb, and I will cut him off from the midst of my people; and ye shall know that I am the LORD.
Ezekiel carried on his prophetic work among the captives of Israel between the years 595 and 574, beginning and closing his work just a little later than Jeremiah. He was a man of the priestly family who was first shown wonderful visions of God's glory and majesty before he began his prophetic work, so that having seen God he would not fear the face of man when sent with awful messages of warning and reproof to the sinners among his own people. The verse stands in the first twenty chapters of Ezekiel, spoken through Ezekiel as God's mouthpiece among the captives in Babylonia by the river Chebar while Jeremiah prophesied in Jerusalem.
In the verse a sign means a memorial or monument, not something unreal or merely symbolic. A sign can also serve as a token, argument, or proof. The Lord sets Himself against and opposes the person who turns away from Him and persists in idolatry. He makes that person a sign and a proverb, an example and a byword, and cuts him off and removes him from among His people, so that the people shall know that He is the LORD.
The verse describes a professed Christian who does not wholly love the law of the Lord but keeps a stumbling-block of iniquity and idols in his heart in place of one of the commandments. Such a one separates himself from God, and still comes formally to seek the Lord for guidance. Such a person does not have great peace or the peace of God. Turning away the ear from hearing the law makes even such a person's prayer an abomination. In its context of Ezekiel 14:1-11, the verse warns that the person with an idol or stumbling-block in the heart is in danger and must recognize his duty to turn from the idol.
The verse means God turns against a professed follower of Christ who receives light that the seventh-day Sabbath kept by Christ and placed in the heart of God's law is binding, yet persists in disregarding it and keeps a rival day never sanctified by Jehovah. That rival observance is an idol cherished in the heart and a stumbling-block showing he does not love God's law, so he cannot have great peace. If he prays while holding to that error and desiring to be established in keeping the popular day instead of the unpopular Sabbath, God answers him according to his stumbling-block, opposes him, and removes him from among His people.