Although God created everything, not everything stayed in the original form due to sin entering in. Just like lions would tear apart a lamb today, we are told when things are restored, "The wolf and the lamb shall feed together, and the lion shall eat straw like the bullock: and dust [shall be] the serpent's meat. They shall not hurt nor destroy in all my holy mountain, saith the LORD" (Isaiah 65:25). So it is with plants. Poison ivy, oak, and sumac, will all return back to being non-poisonous plants. Thorns will not exist allowing us to enjoy roses without getting pricked. So, it is with all of the other plants, like marijuana, that has negative brain affecting results. Such will not exist in the future, but for now, like poison plants, we ought to leave them alone. In fact, God condemns even the possession of such plants, labeled as wormwood (not referencing the plant called wormwood) in Deuteronomy 29:18. This reference refers to death or body destroying plants (Revelation 8:11).