If Judas had free will, how could his betrayal be prophesied in advance?
Judas retained genuine free will; God's foreknowledge did not force his choice. God knew in advance what Judas would freely do when given the opportunity, so prophecy foretold the betrayal. Prophecy then had to be fulfilled, but Judas still had full opportunity to accept, had he wanted to.
Les explains that Judas was not forced into betrayal and was not created to be the betrayer. Judas was not left without a choice; he had just as much choice as the other eleven. God, in His foreknowledge, knew what Judas would do when given the opportunity, and so prophecy foretold it. Once prophecy foretells something, it has to happen, otherwise the book becomes a lie, but that does not remove Judas' free will. He had full opportunity to accept, had he wanted to. David by inspiration prophesied it, and the psalmist foretold that Judas would betray and fall by transgression. Jesus knew from the beginning that Judas was a devil or demon, though the other eleven were fooled. Judas served as treasurer and held the bag, but he never had a spiritual part in the ministry.