How can we reconcile man's free will in his actions with God's guiding whom He wills and leading astray whom He wills, especially in His saying: "That is the guidance of Allah by which He guides whom He wills. And whom Allah leads astray - for him there is no guide," and what is the sin of one whom Allah has led astray?

Allah guides whom He wills by His grace, and misguides whom He wills by His justice, knowledge, and wisdom. Therefore, the question "What is the sin of one whom Allah has led astray?" is not appropriate, especially since the questioner acknowledges the servant's choice and acquisition. Allah has combined His will in guiding and misguiding with the accountability of His servants for their actions, as He states: "And if Allah had willed, He could have made you one nation, but He sends astray whom He wills and guides whom He wills. And you will surely be questioned about what you used to do." (16:93) Man is facilitated for what he was created for, and his actions are by the decree of Allah, but he has a choice and acquisition in them.