Can God lie?

In my experience, Calvinists typically contend that while God can and sometimes does deceive certain people through secondary means (e.g.1 Kgs 20:23), God cannot lie directly. He can deceive through the instrumentality of others (e.g. Ezk 14:9-10) but he can't personally lie. 

On the face of it, that's a makeshift distinction, but in fairness, they simply attempting to adhere to biblical distinctions. And freewill theists are in the same boat. Take stock prooftexts that God cannot lie:

God is not man, that he should lie, or a son of man, that he should change his mind. Has he said, and will he not do it? Or has he spoken, and will he not fulfill it? (Numbers 23:19).

The Glory of Israel will not lie (1 Samuel 15:29).

in the hope of eternal life, which God, who does not lie, promised before the beginning of time (Tit 1:2).

God did this so that, by two unchangeable things in which it is impossible for God to lie (Heb 6:18).

I'll revisit these momentarily, but let's consider a different passage:

Then God said, Take your son, your only son, whom you love—Isaac—and go to the region of Moriah. Sacrifice him there as a burnt offering on a mountain I will show you (Gen 22:2).

1. On the face of it, didn't God lie to Abraham? No point getting bent out of shape by my asking the question. This is not a minor passage. It's from a famous, major incident in Scripture. And it's just as inspired as the contrary prooftexts. 

2. Perhaps someone will object that it's not a lie because it's just a command, whereas a lie must be a declarative sentence. Commands can't be lies because they don't assert or deny anything. Only propositions can be lies. But there are problems with that deflection:

3. It's a hairsplitting distinction that appeals to modern philosophy of language, but why assume Bible writers were operating with that dichotomy? Why assume they confined lies to propositions rather than other kinds of verbal deception? (Or even nonverbal deception?) We can't just impose that stipulation on Scripture.  

4. For that matter, the concept or definition of lying didn't fall from the sky. Even from a philosophical standpoint, it's not a given that lying must be propositional. For instance:

Against the statement condition of L1 it has been objected that the making of a statement is not necessary for lying. Lying to others may be defined as “any form of behavior the function of which is to provide others with false information or to deprive them of true information” (Smith 2004, 14), or as “a successful or unsuccessful deliberate attempt, without forewarning, to create in another a belief which the communicator considers to be untrue” (Vrij 2000, 6). Importantly, this entails that lying can consist of simply withholding information with the intent to deceive, without making any statement at all (Ekman 1985, 28; Scott 2006, 4). Those who make this objection would make lying the same as intentionally deceiving (Ekman 1985, 26).

https://plato.stanford.edu/entries/lying-definition/#ObjTraDefLyi

1. According to Gen 22:2, God issued a command that's verbally deceptive. On a related note, Scripture contains divine predictions of judgment, yet God sometimes relents. Did he keep his word or go back on his word? 

2. This is, in part, an issue about theological method. Assuming inerrancy, when we have apparently discrepant statements in Scripture, what statements function as the benchmark in relation to which we harmonize the other statements? Is Gen 22:2 paradigmatic–or Num 23:19? 

3. One principle is that when Scripture has passages of the same kind, where some are qualified while others are unqualified, we treat the unqualified passages as implicitly qualified by the qualified passages. So, for instance, some oracles of doom are formally unconditional while others are contingent on contrition, so we treat unqualified oracles of doom that don't come to pass, not as false prophecies or failed predictions, but implicitly conditional threats. And that's something to keep in mind when it comes to passages about divine veracity and deception. 

4. A problem with simply quoting 1 Sam 15:29 to settle the issue is that 1 Sam 15:11 says the opposite:

I regret that I have made Saul king, because he has turned away from me and has not carried out my instructions (1 Sam 15:11).

If we take both statements at face value, that generates a contradiction. The standard orthodox explanation is that 1 Sam 15:11 is anthropomorphic. And I agree with that. 

5. Heb 6:18, as formulated, is not an absolute statement, but a specific claim about two unchangeable things: God's promise and oath. That's consistent with either of two positions:

i) It's intrinsically impossible for God to lie, and these two examples are special cases of that general principle. 

ii) It's impossible for God to lie about these two kinds of things, but the statement doesn't address the larger issue of whether God cannot lie under any circumstance whatsoever. 

6. When you look at the prooftexts, there's a common theme. God cannot lie about certain kinds of promises. God cannot lie about his commitment to the ultimate welfare of his people. Here's another example:

What if some were unfaithful? Does their faithlessness nullify the faithfulness of God? By no means! Let God be true though every one were a liar, as it is written,

“That you may be justified in your words,

    and prevail when you are judged.”

(Rom 3:3-4)

That unpacks lying in terms of infidelity. For God to lie, in this context, would mean God was unfaithful to his covenantal obligations. 

Minimally, what the biblical data indicates is that God can't be deceptive about promises of salvation (or damnation). Paradoxically, even in the paradigmatic case of Gen 22, the deceptive command facilitates the covenant with Abraham and other parties to the covenant (future Jews and Gentiles). So the verbal deception is benevolent rather than malevolent. That's like the proverbial white lie, which has a beneficial aim or intent. Telling a necessary lie to do someone good.