Who is Jesus, and what did he do?
It all started with the Creator making a physical form he would use to relate to the physical universe he was going to create. He walked in the garden with Adam and Eve. He ate breakfast with Abraham and Sarah. He talked with Samson's parents. There are many times he met with his human family. But to save them he had to become one of them.
Mary was chosen to be the mother of Jesus. The Creator sacrificed his human form so it could become flesh and blood, to redeem mankind from extinction . The Creator became a father, and his human form truly became his son. And the son was 100% human with all the same characteristics that the first man Adam had. Neither one had the selfish human nature that we inherited from Adam. The son could choose to follow the advice of his father or choose the ways of the world. Fortunately for us he chose to trust in his father. He was not deceived by Satan who told Adam and Eve that death was a transformation into the spirit world where people become like gods and all things are revealed (Gen 3:4-6).
Satan once stood before the throne of the Creator as the accuser of mankind. The penalty for sin is death. But then he went to earth with all his demons to kill the promised child.
In the end Satan succeeded in killing the child but he killed an innocent man. And Jesus rose up alive because death had no authority over him. Through the testimony of witnesses, and his own shed blood, he had paid the price for mankind's salvation. Satan forever lost his right to stand before the throne of the Creator to condemn mankind. Satan was condemned to remain in the physical realm until the time would come that he and his demons would suffer for eternity in a Lake of Fire.
Jesus was lifted up to the throne of his father in the spiritual realm. There he sits at his father's right hand today. He has opened the seals of a scroll that are directing the course of human history until judgement day. He is also preparing a new physical home (earth, planets, and stars) for us. Then he will come back.
At the appointed time he will return to the earth on the clouds, just like he left. He will rescue his people and claim his throne on earth. There will be peace on earth for 1000 years. He will rule the nations with an iron rod (human nature will still exist, but wickedness will be chained up with Satan). The faithful saints of old will be resurrected to take their places in the Kingdom of Christ and will govern the nations of the world. There will be one religion, one government, one King, until the day he gathers all his people up to the sea of glass before the last trumpet sounds. The sea of glass is where the final judgement of all of mankind will take place.
When the new earth and stars are ready the old earth and starts will dissolve away, and all the people who ever lived on earth will stand before the throne to learn of their eternal fate. Life forever in a brand new perfect world, or cremated out of existence in the Lake of Fire and gone forever. Satan and his demons will be trapped in the Lake of Fire for eternity.