Iluvatar made Melkor evil?

[Lief Erikson]

Here's the quote I'm assuming you're using, Cirdan. Please tell me if I'm wrong.

Then Ilúvatar spoke, and he said: 'Mighty are the Ainur, and mightiest among them is Melkor; but that he may know, and all the Ainur, that I am Ilúvatar, those things that ye have sung, I will show them forth, that ye may see what ye have done. And thou, Melkor, shalt see that no theme may be played that hath not its uttermost source in me, nor can any alter the music in my despite. For he that attempteth this shall prove but mine instrument in the devising of things more wonderful, which he himself hath not imagined.'

We have seen from multiple examples in the books that Ilúvatar's character isn't soiled by evil, and that on the contrary, he is the greatest warrior against it. What is shown here is that he has complete power, authority and knowledge. He can turn evil to good, and things that go against his design he can use for his design. Arda remade will be better than the original Arda, probably because of evil's having been permitted. The knowledge of evil and that everyone in this later time are spared from it will make them appreciate more what they have, and make their life in an evil free environment all the more joyous. These things that have been your greatest argument against our point of view, MasterMothra and Cirdan, are in fact great assets in proving the goodness of Ilúvatar's character as well as his knowledge and power.

And thou, Melkor, shalt see that no theme [Italics added] may be played that hath not its uttermost source in me

I'd like to point out again, Cirdan, that this shows a concern for not only the great events, the "framework," but also for the smaller things that happen in the music. All music, all creation comes from Ilúvatar. He doesn't do evil himself, but he permits it, and he does great wonders by changing the discord (Because its source is himself) into something beautiful that supports Ilúvatar's final creation.

Permitting evil and turning it to good doesn't impinge Ilúvatar's character, for he can see all ends. It also doesn't imply that he's involved in committing this evil. Morgoth's treachery was forseen, and because of that, Ilúvatar was able to use it for his own purposes. Everything is spread before him, and everything he turns to righteousness.

Commanding events however in this way doesn't have to disrupt free will at all. Not once in any part of any of the books do I see Ilúvatar or any of the Valar purposely use their power to make others do what they please.

However, I do see frequent times where Ilúvatar punishes evil without disrupting free will. Frodo's casting the Ring into Mount Doom was sufficient proof of Ilúvatar's willingness to use people to accomplish his ends, and his using the Valar to punish Morgoth. Notice that he only did the latter action after Earendil made his voyage and asked for forgiveness for the Noldor. Repentence was the key to Ilúvatar's punishing Morgoth, just as through a humble person he was able to punish Sauron. Not through any means of forcing people to do as they pleased were these things done; Frodo and Earendil had their own choices to make, and made them. Things can be prophesied, but never did the prophesy being fulfilled happen in ways that wouldn't have happen naturally. These events weren't "forced," any more than any of the other events that happened in the books were forced.