I read it and nearly hear it said all the time, that God has conquered the Darkness when His Son embodied sin and died on the Cross for us; so that we could experience eternal life with the Father.

I think Satan is smart enough to know when the Battle has been won, so why does he attack us still with temptation? The Father is all knowing, and all-forgiving so long as you repent and believe in Him and the Son. For Christ told us, that no one can know the Father and not accept the Son; so Faith in Christ and the Father is our being saved. In addition to this, so long as we are believing, and repentant, we have a claim to eternal life. Therefore, why plague us, the Saved?

Satan is not satisfied with the consumerism and pluralism of today. It's not enough that young women and men abandon the ways of purity that are so pleasing to the Father; nor is he content with the people he effectively lures away from the light with lust and flesh that will only decay with time. He has to have more, for the one thing that Satan is when you boil him down (as the Hell Fires eventually shall do anyway) is greed, that need for more, more, and yet still more.

He can never be content, and so he grabs at loose ends thinking that he is winning.

But he has already lost; the Battle was won on the Cross.
Denial won't get the demon any closer to winning, he'll just lose some more, until the Judgement Day when Satan and his band of demons will lose it all like they never thought possible.

You dumb, selfish demon: don't you see I can't be had? I'm a Child of God, and I like it here in the Light just fine.