This question, common as it is, has a serious problem. Namely, it assumes an unbiblical definition of God’s will. Historically, theologians have differentiated between God’s decretal will and His moral will. His decretal will is His sovereign will by which He ordains what actually does come to pass. Systematic theologian Louis Berkhof defined God’s decretal will as, “[T]hat will of God by which He purposes or decrees whatever shall come to pass, whether He wills to accomplish it effectively (causatively), or to permit it to occur through the unrestrained agency of His rational creatures.” Scriptures that speak of God’s decretal will are Job 42:2, Psalm 33:11, Isaiah 46:10, Daniel 4:35, Acts 2:23, 4:28, and Ephesians 1:11. God’s moral will is the expression of His holiness in the form of prescriptions which ought to be obeyed, in should, it is what ought to be done. Again, Berkhof defines God’s moral will as, “[T]he rule of life which God has laid down for His moral creatures, indicating the duties which He enjoins upon them.” All the commands in Scripture are examples of God’s moral will.
This distinction is crucial when we come to ask the question of whether it is God’s will for everyone to be healed. We must first say that it cannot be God’s decretal will for everyone to be healed because everyone is not healed. If God decreed to heal everyone then everyone would be healed, after all, “No purpose of [his] can be thwarted” (Job 42:2) and “None can stay his hand, or say to him ‘What have you done?’” (Daniel 4:35). On the other hand, it does not make sense to say that it is the moral will of God for everyone to be healed, because healing is not a command to be obeyed. It is not a matter of obedience or disobedience whether one is healed or not – all must admit that the actual healing is a work of God, not of the person being healed.
For these reasons, we must answer: no, it is not God’s will for everyone to be healed. But for many, that will not be a satisfactory answer because, after all, we have not addressed any of the Bible’s numerous texts about sickness, disease, and healing! For a discussion of those texts, see my article here.
 Berkhof, Louis. Systematic Theology. Grand Rapids: Eerdmans, 1979, p. 77.
 Ibid. Theologians have also referred to this distinction as between the secret and revealed wills of God, e.g. Bavinck, Herman. Reformed Dogmatics: God and Creation. Vol. II. Grand Rapids: Baker Academic, 2004, p. 242-245.