Of course Calvinists believe hearts make choices...that is a blatant misrepresentation out of ignorance at best, or deviance.
As to the assertion that no Scripture tells us that God is the cause of believing, consider this by R.C. Sproul ...
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Romans 8:7–8 explains that it is impossible for minds set on the flesh to please God and obey Him. People who are not in Christ are in the flesh, so they lack the ability to do the Lord’s will. Since His will for us is that we trust in His promises, unbelievers are incapable in themselves of believing in Christ Jesus for salvation. Furthermore,
John 3:3 says that we cannot even see the kingdom of God unless we are first born again by the Spirit. If we cannot see God’s kingdom, we can by no means enter it. In sum, faith can arise only from a new heart. To put it in theological categories: regeneration precedes faith.
What verse or passage actually teaches that regeneration precedes faith. I am quite familiar with the reformed doctrine of such, but where is the teaching found?
In fact, Scripture teaches the exact opposite. Taught by Paul.
In Eph 2:5 - made us alive with Christ even when we were dead in transgressions—it is by grace you have been saved.
I hope we agree that the phrase "made us alive" means regeneration, or the new birth.
OK, then the phrase at the end of the verse, "it is by grace you have been saved".
That phrase is simply a clarification of the first phrase, "made us alive".
iow, they are equivalent ideas. They are essentially synonymous. You can't have one without the other.
If one has been saved, they have been made alive.
If one has been made alive, they are saved.
Now, Eph 2:8 - For it is by grace you have been saved, through faith—and this is not from yourselves, it is the gift of God—
Here we find the specific order of things; "you have been saved through faith".
In order to be saved "through faith", it should be obvious that faith precedes salvation. And v.5 reveals that regeneration and being saved are the same thing, or at least occur together.
Therefore, faith precedes regeneration.
Faith is a gift of the Lord to undeserving people
No need to use the word "undeserving". All humans are undeserving of salvation.
And, using the noun "faith", it IS a gift. But the ACTION (verb) of believing is NOT a gift of God, by which the so-called "elect" respond to the gospel.
2 Thess 2:11 "And for this reason God will send them strong delusion, that they should believe the lie,"
Did you note the previous verse? I thought not. So here it is: and all the ways that wickedness deceives those who are perishing.
They perish because they refused to love the truth and so be saved.
Here we see a very clear statement about their free will to reject the truth, by which they would have been saved.
So the phrase in v.11 "and for this reason" refers to the FACT that because they refused (volition) to love (believe) the truth, they will perish.
So, why does God send these specific people a "strong delusion" so that they would believe a lie? Because they refused to love the truth.
God doesn't do this for every unbeliever who ends up in hell. He does do it for those who have heard the truth and refused to believe or love it.
To be specific, no Scripture that supports the Calvinist claims regarding election.
If God can cause unbelief, how much more can He cause belief?
See? This definitely shows that you've misunderstood 2 Thess 2:10,11. It clearly does NOT say that God causes unbelief.
In fact, it states the exact opposite; that men REFUSE TO LOVE THE TRUTH, by which they perish. It is FOR THAT REASON that God sends them a strong delusion so they will believe the lie. They are already destined to perish, for REFUSING TO LOVE THE TRUTH AND SO BE SAVED.
He is the cause of belief and leaves no room for boasting.
Free will choice to love the truth and believe it also leaves no room for boasting.
However, there are no verses that tell us that God is the cause of belief.
If that were true, then the human race is nothing more than puppets, or pre-programmed robots.
I know the Calvinists howl at this and will strongly deny that, but there is no other option, if God is the cause of one's believing. You just won't admit it.