If your assumption is correct, the answer is: because God predestined him to hell.

Historically, many Presbyterians have believed in double-decree predestination, which states that before creation, God predestined some people to salvation and others to perdition. The damned end up in hell because God created them with that destiny in mind.

The doctrine bows unreservedly before God’s absolute sovereignty: God decided to create some for heaven and some for hell, and whatever God decides is right.

Many other Presbyterians have found the doctrine’s symmetry unpersuasive. We go to heaven because God chose us for salvation: but there are a couple of reasons for hesitating to believe that we go to hell because God chose us for damnation.

First, the scriptures that make explicit declarations about predestination talk about predestination to life (Romans 8:29-30; Ephesians 1:3-5). There are no symmetrical texts about how God chose others for damnation (one might propose Romans 9, but Paul’s language there is hypothetical, rather than declarative).

Second, it is hard to reconcile double predestination with the doctrine of God’s love for the world. Suppose we are worried about the soul of our good friend Bob. Our love for Bob means that we want him to be saved. But if Bob has been predestined to hell, what could it mean to say that God loves Bob, and wants him to be damned?

If these reasons make us hesitate to embrace double-decree predestination, we will also hesitate to assume God created Judas intending his damnation. Jesus spoke about his death as the fulfillment of scripture (e.g., Matthew 26:23, 31, 54, 56), but these texts are far from saying that God predestined Judas to betray Jesus. So we should suppose that just as God loves and intends to save the world, God loves and intends to save Judas.

When Matthew juxtaposes the stories of Peter and Judas (26:69 – 27:10), he shows us two followers of Jesus lost in (apparently irredeemable) failure and despair. Matthew never mentions either name again: one could easily assume that they are gone forever, and indeed damned. Except that Matthew gives us one more clue: the eleven disciples who saw the risen Jesus (28:16). Eleven? Why not twelve? Ah: because Peter and Judas were gone. But then, why not ten? Because Peter came back. Hmmm: if that’s the case, doesn’t that press us to ask, suppose Judas had come back as well?