According to Islam, humans and jinns have free will and can be good or evil.
In Islam it's said the Savior will kill the evil, Satan. One of the prophet's grandsons was asked if this happens, how will God put people to test of the evil if Satan doesn't exist anymore. He replied the Jinn Satan will be killed while human evil will still exist and the judgment will be accordingly.
Human evil (Satan) is the sum of all negative thinking and negative attributes of humanity, that differ from a human to another according to his ethical and non ethical beliefs. For example greed, envy, slander, lying, betrayal etc… This evil can't be eliminated because it's inside our brains. It can only be weakened when a society follows truly God's orders.
Jinn evil on the other hand will get killed later. Until now nobody made a statement about the true nature of Jinns. At time of prophet Mohammad (sas) he didn't explain Jinn's nature because prophets were asked to talk to people according to their knowledge level and Jinns true nature was not meant to be unveiled at that time, but to future generations like our. Now that we know about the microscopic world, we are finally able to define the concept of Jinn and Jinn's evil (Satan).
Fact # 1 : Only about 10% of the cells in our body are human – the vast majority are Bacteria. Together, we make what we really are: a symbiosis between bacteria and human as a host, both dependent on each other.
Fact # 2 : Bacteria can influence our mental health.
Fact # 3 : Bacteria can be good, neutral, or evil (pathogenic).
Fact # 4 : Bacteria have a free will and they decide to mutate into bad bacteria (pathogenic) by actively allowing bad genes in form of plasmid to enter inside them.
Fact # 4 : Is Ouroboros the alchemical interpretation of plasmid at times they didn't have an electron microscope?
Fact # 5 : Religions and clearly Quran talked about 2 living organisms, that have free will an hence will face judgment, humans and Jinns. Since Bacteria have free will, Jinns must be Bacteria without doubt according to Quran or vice versa if Jinns have free will according to Quran and Jinns are nothing but bacteria, so bacteria have free will.
Fact # 6 : Prophet Mohammad said a lot regarding pathogenic bacteria, but named them under the collective word Satan. "Don't keep garbage inside your house over the night, Satan dwells inside, take garbage out of the house as long it's daylight" (scientifically speaking, at his time garbage was made of organic substances, they had no plastic garbage bags, so telling people to take it out during daylight is to prevent bad fermenting bacteria and yeasts to get activated in the dark during the night), "keep your nails short, Satan dwells under long nails" , "shorten moustaches at most every forty days, otherwise Satan dwells there", etc…
Based on the above facts, a new interpretation of evil and Satan can be hypothesised. Jinns (Bacteria) are like humans, they can live according to God's order, means peaceful to others or become dissolute to God's order, means malicious (pathogenic). Since only bacteria can choose to be good or malicious (pathogenic) by incorporating the bad genes we can conclude, that Jinns are actually bacteria. The evil, Satan was a bacteria and it became malicious (pathogenic), harming people and every other living systems like animals and plants. The awaited Savior will make an end to its existence, but malicious human beings will still exist and try to negatively influence others by their malicious ethical behavior and insinuation.