If I had a nickel for every time a Calvinist said to me "free will isn't in the Bible," I'd have a whole Nickelback album.
I do not accept the Trinity because it is explicitly declared in Scripture.
And this is true of libertarian freedom.
Hence, the philosophical notion of libertarian freedom is under the same umbrella.
The Trinity is deduced from Scripture not explicitly stated, and free will can also be conclusively deduced from Scripture.
First let's talk a little about what free will is not—
1. It's not the ability to do absolutely anything.
2. It's not the guarantee of no influencing forces.
3. It's not the ability to produce self-righteousness.
4. It is not randomness—this straw man caricature would mean choice is not under control of an agent, like a slot machine.
Free will is the limited ability to select between certain limited options as ordained and circumscribed by God's created order.
Now let's take a fairly mundane seeming passage and extrapolate some ideas from it.
3 But God came to Abimelech in a dream by night, and said to him, "Indeed you are a dead man because of the woman whom you have taken, for she is a man's wife."
4 But Abimelech had not come near her; and he said, "Lord, will You slay a righteous nation also?
5 "Did he not say to me,`She is my sister '? And she, even she herself said,`He is my brother.' In the integrity of my heart and innocence of my hands I have done this."
6 And God said to him in a dream, "Yes, I know that you did this in the integrity of your heart. For I also withheld you from sinning against Me; therefore I did not let you touch her.
7 "Now therefore, restore the man's wife; for he is a prophet, and he will pray for you and you shall live. But if you do not restore her, know that you shall surely die, you and all who are yours." (Gen 20:3-7 NKJ)
Just as the Trinity can be deduced from whatever passages you want to cite, so true autonomous decision can be from this passage (as well as hundreds of others, but this passage is sufficient and a good example).
This is a long setup but bear with me. At first God says to Abimelech that he is a dead man because he has sinned. Abimelech answers and implies that this is too harsh a judgment in the light of his current limitations of understanding the situation. Abimelech then declares he is innocent. In verse 6, God does not say Abimelech is wrong, but rather affirms that Abimelech is actually correct on this issue. He has done this "in the integrity" of his heart. Then God says he has somehow kept Abimelech from sinning so far as an act of mercy because of ignorance. But now Abimelech is no longer considered ignorant, as he has been warned, so we end with verse 7 in which God lays out two different outcomes that are both indicated to be a real possibility and determined by the choice Abimelech makes.
Honesty is an attribute of God, and honesty in communication is necessary if you want to be understood in the way you intend to say something. "God is not a man that he should lie," says the Divine. That is, in general, if you wish to convey information and not mislead someone, you actually have to mean what you say. We cannot claim Abimelech would understand this passage in any deterministic way, and if determinism were true it would not be beyond the capacity of God to phrase this in a deterministic way or even to explain that Abimelech actually has no libertarian choice in the matter and there are not two real, viable outcomes as God indicated, where Abimelech either "surely dies" or he will in fact "live" although he was declared dead already, which in this case would indicate he had a pending "death sentence," or ban, on him.
Now the truth about determinism is a sneaky one, because no matter how you phrase something to sound like autonomy, you can always just claim it only sounds that way as some kind of illusion. But the default position of any text should not to be take the plain meaning as an illusion, but to take it as meaning what it says, unless we have strong overriding context. With proponents of determinism, a small percentage of Bible verses that could possibly be interpreted as deterministic are used as an overriding lens to reinterpret a much, much larger majority percentage of thousands of passages that are made to sound deliberately as if choice were two or more actual outcomes decided by the individual, instead of pre-decided by God.
And this overriding persupposition becomes so second nature to the Calvinist, that, in my interaction with determinists anyway, they almost seem to think it's the natural way to interpret choices in Scripture as necessarily deterministic when that's actually not the default way to understand them.
If God wanted to convey a deterministic meaning of any kind to Abimelech it would have been easy, simple and clear to simply phrase what God says to Abimelech in a deterministic way, "I have chosen you to sin," or "you will go on and do what I have decided for you to do," or "you must fulfill your destiny and this is what it will be." God does not choose any of those easy options which would be honest and clear, to phrase something deliberately in a way that sounds non-deterministic, and this is not by any definition the honest way of communicating. Abimelech, if Calvinism were true, would have been misled by God.
So although we have verses where Jesus says "the only true God" in reference to his Father, we take the higher percentage of verses and reinterpret the lower percentage of verses, to justify our interpretation that Jesus himself is the only true God as well. In the same way Scripture actually ends up directly supporting the idea of libertarian freedom, instead of directly opposing the idea of libertarian freedom, as many Calvinists contend.
So by using the exact same "hermeneutics" we would use to come to a deduction of the Trinity, we come with this consistent and predominantly used method of interpreting the Bible, to describing choices as multiple potential outcomes determined by the agent.
A Calvinist cannot "walk through the text" when reading from "the original Hebrew" and stay a consistent exhaustive divine determinist in Genesis chapter 20.
Peace to Spiritual Israel.