This lesson is about warnings from God. Does God warn human beings about their behaviour and its consequences? If so, what does this say about the idea that God has already decided each person’s destiny —saved or doomed regardless of that person’s behaviour?
Yes. The Bible warns people to repent of sin and be saved, that their souls might live and not die. They are warned that if they don't do this, they will be condemned and will perish.
Even the famous verse John 3:16 has an implied warning in the words "should not perish" People should not perish but they will if they don't believe in Jesus God’s Son.
"God so loved the world that he gave his only begotten Son that whoever believes in him should not perish but have everlasting life" (John 3:16).
This has always been God’s stand. Obey him in faith and love, and you will live. Otherwise your soul will perish and die. For example, read Ezekiel 18:21-32 which includes these phrases...
¶“18If the wicked turns from his ways he shall not die... But when a righteous man turns from his righteousness and commits sin he will die... Repent and turn away from your iniquity so that sin may not become a stumbling block to you... Make for yourselves a new spirit for why will you die O house of Israel?” (See Ezekiel 18:21-32).
We read many such warnings in the Scriptures. God, as a mark of his love, has given humanity many timely warnings to flee from his wrath and be saved by his grace
Another example is Revelation 2:18-25 warning Jezebel and her disciples to repent or else perish.
God decided to destroy Ninevah, but God changed his mind when he saw the people’s repentance (Jonah chapter 3). The warnings spoken by Jonah had wrought this change in the people’s ways. So God changed his intentions accordingly. His warnings caused their salvation.
Jesus made the point that there are no special cases. Referring to events that people believed to be punishment by God, he warned, "Unless you repent, you will all likewise perish" (Luke 13:3,5)
I could add dozens of examples of warnings God has given. What are we to make of God’s warnings if what Calvinism says is true?
Calvinism holds that God has already decided which individuals will be saved, and these cannot possibly be damned. As for the rest, whom God did not choose for salvation, they are damned and cannot possibly be saved.
If that is true, surely all the warnings are meaningless —because whoever may read them, the saved do not need them, and the lost cannot heed them.
Would God warn people, "Repent or perish!" when he has already decided for each person whether that person will repent or perish, and that person has no say in what God has decided?
Yes. If the saved can lose their salvation by turning from their righteousness then certainly they need warnings. Only if they cannot be lost would they need no warnings.
We have such warnings as James 5:19-20 and Hebrews 10:26-31 which are warnings clearly addressed to the saved and sanctified. This shows that the saved can be lost else why the warnings?
¶“26Since we have received knowledge of the truth, we must not willingly continue to sin. If we do, no sacrifice for sins will be left for us. 27We can only be terrified, expecting the fire and fury of a judgment that will consume those who rebel. 28[We read in] the law of Moses that those who rebel against it die without mercy or appeal on [the testimony of] two or three witnesses. 29Don't you think that a far worse punishment is merited by one who tramples on the Son of God? One who has been made holy by the blood of Christ’s covenant, [should not] treat that blood as unholy. That would insult the Spirit of grace” (Hebrews 10:26-31).
Why tell a saved person to avoid God’s fire and fury, if God has already irrevocably decided that person will be saved from it? Why tell a saved person not to lose salvation, if that person cannot lose it?
Yes. If the lost can escape their damnation by turning from their iniquity and obeying the truth, then they too need warnings and are capable of heeding them (Ezekiel 18:20-23).
The warning, "Stop or I'll shoot!" is sensible if the person warned is allowed to stop, and having stopped is not shot. Likewise, the warning "Repent or perish!" is sensible if the person is allowed to repent and having repented does not perish.
Why tell a lost person not to be lost if God has already irrevocably decided that person will be lost? Why tell a lost person to be saved, if that person cannot be saved?
The fact that God gives you warnings shows that you can make changes in your life and destiny. Are you saved? Then God warns you not to lose that salvation. Are you lost? Then God warns you to turn from your sin and be saved. God gives you warnings because you need them and can heed them.