Ephesians Chap. 2:1–3: "And you hath He quickened, who were dead in trespasses and sins, wherein in time past you walked, according to the age of this world, according to the prince (ruler) of the power (or authority) of the air, the spirit that now works in the children of disobedience; among whom also we all had our conversation in times past, in the lusts of our flesh, fulfilling the desires of the flesh, and of the mind; and were by nature the children of wrath even as others.” Part of the difficulty in this passage is that in English it appears that prince and spirit refer to the same thing; but in Greek they clearly do not refer to the same thing. Prince (or ruler) is accusative, and spirit is genitive. Both would have to be in the accusative or both in the genitive to be referring to the same thing. Grammatically speaking, prince and spirit are not in apposition to each other, meaning “they are two words that are not grammatically parallel, having the same referent.”The authority, or power, is the authority or power given to Satan [Luke 22:53; Acts 26:18; Col. 1:13]. Satan is the ruler whose authority is exercised in the realm of the air. He is the leader of those spiritual hosts of wickedness in the heavenly places (Eph. 6:12). The addition of the preposition ‘of’ before ‘the spirit,’ implies that the devil is not himself ‘the spirit that now works in the sons of disobedience,’ but that he is the prince or ruler of that spirit. The ‘spirit’ in this sense then is a kind of ‘spirit of the age.’ The ‘spirit of the age’ is under the control and direction of the devil. So ... I am not denying that Satan has power and authority here in this world.My caution in the discussion is to make sure we understood that whatever authority Satan has as ruler in this world, or any power he possesses in the world, is an authority with definite parameters assigned to him by God alone. Here is how Calvin interpreted this passage:According to the prince of the power of the air = “[Paul] now proceeds farther, and explains the cause of our corruption to be the dominion which the devil exercises over us. … all men who live according to the world, that is, according to the inclinations of their flesh, are here declared to fight under the reign of Satan.… As the children of God have one head, so have the wicked [Gen.3:15 — your seed and her Seed]; for each of the classes forms a distinct body. [God has assigned to Satan] the dominion over all wicked beings, [where] ungodliness is represented as an unbroken mass. … [but it is not] as if Satan could do anything without the Divine permission. Paul does not allow him the highest authority, which belongs to the will of God alone, but merely a tyranny which God permits him to exercise. What is Satan but God’s executioner to punish man’s ingratitude? This is implied in Paul’s language, when he represents the success of Satan as confined to unbelievers; for the children of God are thus exempted from his power. If this be true, it follows that Satan does nothing but under the control of a superior: and that he is not [an autonomous] unlimited monarch.” -- Calvin, J., & Pringle, W. (2010). Commentaries on the Epistles of Paul to the Galatians and Ephesians (pp. 220–221). Bellingham, WA: Logos Bible Software. I think we can agree that all that Satan does is by God’s permission. Therefore, if what Satan does is to deceive the unbeliever, and have dominion over the lives of wicked unregenerate humans, convincing them of the great benefit of living for the flesh instead of living for God, then I would suggest that any discussion about the unbeliever having free will is rather silly. Unbeliever’s clearly do not have free will if Satan, with God’s permission, works in them to do Satan’s (and hence, God’s) will. Now, there is another passage in 2 Timothy 2:26 that is similar in difficulty to this one that is along the same vein as well.2 Timothy 2:24-26: "And a servant of the Lord must not quarrel but be gentle to all, able to teach, patient, in humility correcting those who are in opposition, if God perhaps will grant them repentance, so that they may know the truth, and that they may come to their senses and escape the snare of the devil, having been taken captive by him to do his will." In English, again, it could appear that this is saying that unbelievers have been taken captive by the devil to do the devil’s will. Clearly, the devil has laid the snare for them. These persons have been entrapped by the snare the devil has laid; BUT, those who are no longer ensnared are enabled, at their awaking sober, to escape. But doesn’t Paul mean that the taking captive of these men by him [Satan] only takes place as far as God permits, and according to His will? The difficulty is of course to determine whether the pronouns are used of the same person, [God] or of different persons (the first of Satan and the second of God).Most commentators agree that the second pronoun ‘his’ refers to the remoter antecedent (God) and not the nearer one (the devil). This would render the passage as “taken prisoners by God’s servant (the devil) according to His (God’s) will,’ ... so as to follow God’s purpose. But, for those who are no longer held in captivity, who have come to their senses, and escaped that snare — (believers) — their capture is overruled by God. So God uses the devil to capture and ensnare some, but overpowers the capture and ensnarement of others. Again, one would have to seriously consider exactly how effective the supposed free will is of either those ensnared and held captive by the devil, or those freed by God from that captivity. -- Alford, H. (1976). Alford’s Greek Testament: an exegetical and critical commentary (Vol. 3, p. 390). Grand Rapids, MI: Guardian Press.