According to Genesis 1:31, all that God created was good. However, not only in the human realm, but also in nature, there is much that seems violent and evil. Darwin, for example, could not conceive of a good God creating an animal such as the Ichneumon Wasp, or the Cuckoo. Could it be that the world, at least in parts, is a creation of the devil? If this is a heresy, what is it called?
A most definite no.
Satan does not have the power to create; only God does. Theologians for centuries have been using the phrase ex nihilo to describe God's creative activities. That saying is fine as far as it goes, but I suggest that a better expression than "God created all things out of nothing" is
God created all things out of the fullness of his being.
If God is who the Bible says he is, then he is eternal, having no beginning and no end. He is the Alpha and Omega, the first and the last. In other words there never was (nor will there ever be) a "time" when God did not exist. For all eternity, Father, Son, and Holy Spirit enjoyed the perfect communion of love, as only the Triune God could.
Time, on the other hand, is a creation of God. Christians and non-Christians alike have difficulty conceiving of a "time" when all there was, was God, but according to the Judeo-Christian Scriptures, time and eternity did not coexist until God created time and space by fiat, which we read about in Genesis, Chapters 1 and 2. Much later in God's revelation, he made clear that after Adam's fall, God would one day make all things new, and that in newness they would remain forever, as they originally were intended.
Jesus had an interesting "take" on his relation to eternity. In a famous confrontation with his critics, Jesus said,
Before Abraham was born, I am (John 8:58).
Whether Jesus was claiming here to be the Great I AM of Exodus 3:14 is perhaps immaterial in the context of this question. What is clear is that Jesus was claiming to have been alive eternally, and no one but God is eternal. Ergo, Jesus was claiming divinity.
As for the devil (aka Satan, aka Beelzebub, aka Mephistopheles), even he had a beginning and at one time was perhaps the epitome of all angelic beings; that is, until he was filled with pride and determined to be "like" God Most High, whereupon God cast him out of heaven. One day God will consign him to the place prepared for him and those who joined him in their rebellion against God.
God's image bearers, too, can live eternally, according to Jesus' words in John Chapter 3 and elsewhere, but each image bearer began his or her life in time and space. Eternal life, however, is a gift of God, just as the gift of salvation is purely a gift of God's grace and not of works (Ephesians 2:8-9).
Satan does, however, have the temporary ability to kill, steal, and destroy what God has created, just as the sheep stealer enters the sheepfold belonging to someone else and helps himself (see the Gospel of John, Chapter 10). Satan's days are numbered however. His attempts to destroy what God is building on earth, the quintessence of which is his holy catholic (i.e., universal) church comprised of all true Christians, will one day come to an end, when God wages the ultimate battle in which Satan will be defeated forever.
In conclusion, I've thought for a long time about why God in Genesis began his creative work on the planet we call Earth when it was "without form and void [, with] darkness covering the face of the deep." One possibility is that Satan and his minions, once they were excommunicated from heaven forever, deliberately despoiled what God had created, and so God, who makes all things new (and not all new things) re-created what Satan had destroyed. This re-creation presages, perhaps, what God will do when evil is defeated once and for all, since the promise in Revelation is that he will destroy the corrupted heavens and earth and create a new heavens and a new earth in which only righteousness dwells.