Jim Meritt of Infidels includes on his "List of Biblical Contradictions" the question, "[Does] God change?" The EvilBible also makes this claim. Don Morgan's list also claims this is a contradiction.
|“|| James 1:17 Every good gift and every perfect gift is from above, and cometh down from the Father of lights, with whom is no variableness, neither shadow of turning.
Malachi 3:6 For I am the LORD, I change not; therefore ye sons of Jacob are not consumed.
Ezekiel 24:14 I the Lord have spoken it: it shall come to pass, and I will do it; I will not go back, neither will I spare, neither will I repent; according to thy ways, and according to thy doings, shall they judge thee, saith the Lord God.
Numbers 23:19 God is not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do it? or hath he spoken, and shall he not make it good?
Genesis 6:6 And it repented the LORD that he had made man on the earth, and it grieved him at his heart.
Jonah 3:10 And God saw their works, that they turned from their evil way; and God repented of the evil, that he had said that he would do unto them; and he did it not.
1 Samuel 2:30-31 Wherefore the Lord God of Israel saith, I said indeed that thy house, and the house of thy father, should walk before me for ever: but now the Lord saith, Be it far from me; for them that honour me I will honour, and they that despise me shall be lightly esteemed. Behold, the days come, that I will cut off thine arm, and the arm of thy father's house, that there shall not be an old man in thine house.
2 Kings 20:1-6 In those days was Hezekiah sick unto death. And the prophet Isaiah the son of Amoz came to him, and said unto him, Thus saith the Lord, Set thine house in order; for thou shalt die, and not live. Then he turned his face to the wall, and prayed unto the Lord, saying, I beseech thee, O Lord, remember now how I have walked before thee in truth and with a perfect heart, and have done that which is good in thy sight. And Hezekiah wept sore. And it came to pass, afore Isaiah was gone out into the middle court, that the word of the Lord came to him, saying, Turn again, and tell Hezekiah the captain of my people, Thus saith the Lord, the God of David thy father, I have heard thy prayer, I have seen thy tears: behold, I will heal thee: on the third day thou shalt go up unto the house of the Lord. And I will add unto thy days fifteen years; and I will deliver thee and this city out of the hand of the king of Assyria; and I will defend this city for mine own sake, and for my servant David's sake.
Exodus 33:1-14 And the Lord said unto Moses, Depart, and go up hence, thou and the people which thou hast brought up out of the land of Egypt, unto the land which I sware unto Abraham, to Isaac, and to Jacob, saying, Unto thy seed will I give it: And I will send an angel before thee; and I will drive out the Canaanite, the Amorite, and the Hittite, and the Perizzite, the Hivite, and the Jebusite: Unto a land flowing with milk and honey: for I will not go up in the midst of thee; for thou art a stiffnecked people: lest I consume thee in the way. And when the people heard these evil tidings, they mourned: and no man did put on him his ornaments. For the Lord had said unto Moses, Say unto the children of Israel, Ye are a stiffnecked people: I will come up into the midst of thee in a moment, and consume thee: therefore now put off thy ornaments from thee, that I may know what to do unto thee. And the children of Israel stripped themselves of their ornaments by the mount Horeb. And Moses took the tabernacle, and pitched it without the camp, afar off from the camp, and called it the Tabernacle of the congregation. And it came to pass, that every one which sought the Lord went out unto the tabernacle of the congregation, which was without the camp. And it came to pass, when Moses went out unto the tabernacle, that all the people rose up, and stood every man at his tent door, and looked after Moses, until he was gone into the tabernacle. And it came to pass, as Moses entered into the tabernacle, the cloudy pillar descended, and stood at the door of the tabernacle, and the Lord talked with Moses. And all the people saw the cloudy pillar stand at the tabernacle door: and all the people rose up and worshipped, every man in his tent door. And the Lord spake unto Moses face to face, as a man speaketh unto his friend. And he turned again into the camp: but his servant Joshua, the son of Nun, a young man, departed not out of the tabernacle. And Moses said unto the Lord, See, thou sayest unto me, Bring up this people: and thou hast not let me know whom thou wilt send with me. Yet thou hast said, I know thee by name, and thou hast also found grace in my sight. Now therefore, I pray thee, if I have found grace in thy sight, shew me now thy way, that I may know thee, that I may find grace in thy sight: and consider that this nation is thy people. And he said, My presence shall go with thee, and I will give thee rest.
1 Samuel 15:29 And also the Strength of Israel will not lie nor repent: for he is not a man, that he should repent.
Perhaps the best answer is that provided by CARM, "When God says that He does not change, He is speaking about His nature and character. But this does not mean that He cannot change how He works with people throughout history." For a similar passage to Malachi 3:6, see Psalms 89:34 - "My covenant will I not break, nor alter the thing that is gone out of my lips." Here it is explained why the "sons of Jacob are not consumed" and what change is being discussed.
|“|| Psalms 89:29 His seed also will I make to endure for ever, and his throne as the days of heaven.
30 If his children forsake my law, and walk not in my judgments;
31 If they break my statutes, and keep not my commandments;
32 Then will I visit their transgression with the rod, and their iniquity with stripes.
33 Nevertheless my lovingkindness will I not utterly take from him, nor suffer my faithfulness to fail.
34 My covenant will I not break, nor alter the thing that is gone out of my lips.
35 Once have I sworn by my holiness that I will not lie unto David.
36 His seed shall endure for ever, and his throne as the sun before me.
Clearly God by saying "I change not" as seen in the above passage is referring to His covenants with Abraham, Jacob, and David to preserve a lineage as His chosen people. It is for this reason that God numerous times when disgusted with Israel did not wipe them off the face of the planet (which judging by his frustration levels expressed numerous times, He would certainly have liked to do). Instead as God promised David, He used punishments (v. 32) but He refused to break His covenant that David's seed would endure for ever. (v. 36)
This can also be seen from the following passage with Moses where God ends up "repenting" for punishing Israel's idolatry of the golden calf:
|“|| Exodus 32:11 And Moses besought the LORD his God, and said, LORD, why doth thy wrath wax hot against thy people, which thou hast brought forth out of the land of Egypt with great power, and with a mighty hand?
12 Wherefore should the Egyptians speak, and say, For mischief did he bring them out, to slay them in the mountains, and to consume them from the face of the earth? Turn from thy fierce wrath, and repent of this evil against thy people.
13 Remember Abraham, Isaac, and Israel, thy servants, to whom thou swarest by thine own self, and saidst unto them, I will multiply your seed as the stars of heaven, and all this land that I have spoken of will I give unto your seed, and they shall inherit it for ever.
14 And the LORD repented of the evil which he thought to do unto his people.
God does not change His covenants and promises, and this is repeated throughout the Bible:
|“|| Numbers 23:19 God is not a man, that he should lie; neither the son of man, that he should repent: hath he said, and shall he not do it? or hath he spoken, and shall he not make it good?
Lamentations 3:22 It is of the LORD'S mercies that we are not consumed, because his compassions fail not.
Romans 11:29 For the gifts and calling of God are without repentance.
While God does not regret doing wrong (since God does not sin or do wrong), He can be seen to regret justifiable punishments enacted on evil human beings. (e.g. Ex. 32:14; Deut. 32:36; Jg. 2:18; 2 Sam. 24:16; 1 Chr. 24:15; Ps. 90:13; 106:45; 135:14; Jer. 26:19; Am. 7:3-6; Jon. 3:10)
Some of the confusion may be caused the archaic usage by the KJV of the word "repent" which is used to mean God simply being sorrowful, even for executing just punishments, and usage of the word "evil" which is used simply to mean a harsh punishment. See for example its usage in Jeremiah 18:8-13 where God says He will "repent of the evil" He does in punishing evil nations as long as they turn from their evil, and that if they do evil then He will "repent of the good". In KJV-speak, verse 12 even continues with "Thus saith the Lord; Behold I frame evil against you... return ye now every one from his evil way, and make your ways and your doings good."
|“|| Jeremiah 18:8 If that nation, against whom I have pronounced, turn from their evil, I will repent of the evil that I thought to do unto them.
9 And at what instant I shall speak concerning a nation, and concerning a kingdom, to build and to plant it;
10 If it do evil in my sight, that it obey not my voice, then I will repent of the good, wherewith I said I would benefit them.
11 ¶ Now therefore go to, speak to the men of Judah, and to the inhabitants of Jerusalem, saying, Thus saith the LORD; Behold, I frame evil against you, and devise a device against you: return ye now every one from his evil way, and make your ways and your doings good.
12 And they said, There is no hope: but we will walk after our own devices, and we will every one do the imagination of his evil heart.
Unfortunately, the KJV's continued popularity results in confusion over archaic wording that is centuries out of date. Perhaps people forget that words in the English language meant different things when the KJV was translated in 1611 than they do now, over 400 years later.