Calvin writes on Amos 3:
Now as to the word repent, as applied to God, let us know, as it has been elsewhere stated, that God changes not his purpose so as to retract what he has once determined. He indeed knew what he would do before he showed the vision to his Prophet Amos: but he accommodates himself to the measure of men’s understanding, when he mentions such changes. It was then the eternal purpose of God, to threaten the people, to show tokens of his displeasure, and yet to suspend for a time his vengeance, that their perverseness might be the more inexcusable. But in the meantime, as this was without advantage, he sets forth another thing — that he was already armed to execute his vengeance. God then does not relate what he had decreed, but what the Israelites deserved, and what punishment or reward was due to them. When, therefore, God begins to inflict punishment on sinners, it is as though he intended to execute fully his vengeance; he however forms a purpose in himself, but that is hid from us. As soon then as he lifts up his finger, we ought to regard it as owing to his mercy, that we are not instantly reduced to nothing; when it so happens, it is as though he changed his purpose, or as though he withheld his hand. This then ought to be borne in mind, when the prophet says, that God created locusts to devour all the grass, but that he suppliantly entreated God to put an end to this calamity. He then adds, that it repented God, not that there was any change of mind in God, but because God suddenly and beyond hope suspended the vengeance which was near at hand. It shall not then be
In Amos 7:3, the context is that God wants to judge Israel for wickedness. God first begins forming locusts, but Amos intercedes (“please forgive!”), and God repents. Then God begins calling fire on Israel. Amos again intercedes (“please forgive!”), and God repents again. Then God shows Amos a plumb line (used for demolishing buildings), and declares against Israel. The chapter ends reading:
Amo 7:17 Therefore thus says the LORD: “‘Your wife shall be a prostitute in the city, and your sons and your daughters shall fall by the sword, and your land shall be divided up with a measuring line; you yourself shall die in an unclean land, and Israel shall surely go into exile away from its land.'”
The first part might have a period of time implied between pronouncements. It seems to be implied that Amos is recounting a history of his intercessions for Israel. God is described as having begun to build a judgment by locusts. God has started doing something, that according to Calvin, God knew would never happen. God then calls on fire, another judgment, according to Calvin, God knew would never happen. This is all to inspire repentance, again according to Calvin, that never occurs. God ends up judging Israel very harshly.
Calvin’s reading is a very confused reading of this text. God delays knowing full well the reasons for His delays will never be realized. The people are never assumed to have repented, and never do repent. God’s repentance is attributed to Amos’ intercessions, and never hinted to be due to Calvin’s secret reasonings. The text just is not written with John Calvin’s theology in mind.
Instead, the text is written showing God’s mercy due to intercessory prayer, and how futile God’s mercy had been in inspiring repentance. God’s subsequent wrath is more defensible, as God had given every chance of repentance. In this version of events, God is not beginning tasks He will never fulfill. God is not having Amos write in a misleading manner. God is not taking actions for reasons that He knows will never materialize.