It appears it was at his courtroom trial in Heaven that Satan stuck his chest out and bragged that if he had been given more time and resources then he could have taken all of God's angels away from Him in the war- not just a fraction but all of them. His "logical" but flawed premise was based on the fact that no one could love God for who He was and continue to serve Him for eternity. Satan could offer each of them so much more than God did. God disagreed with Satan and the matter was in dispute for quite some time with Satan continually making an issue of it and influencing others in the heavenly realm to wonder if Satan was right or not. God came up with a plan. God would create human-beings with free will and choice. God would have them populate planet earth and each individual would then have a choice to love and serve God or not. It was a simple plan of ownership. Each individual would either be owned by God or by Satan. One could say that the spiritual war that started in Heaven spread to earth.

The planet earth was already in existence at that time but now God made it habitable for human occupation. Lucifer was given a temporary visitor's pass to come and go from Heaven as he wished to falsely accuse the righteous ones on earth. Lucifer commanded his fallen angels to join him on planet earth for a long-time war against God. However, some of his angels will remain in Hades until they are loosed for a short time in the future
(Revelation chapter 9). Another scripture states, "...for if God spared not the angels that sinned, but cast them down to Hades, and delivered them into chains of darkness, to be reserved unto judgment..."
(2 Peter 2:4).

God proposed this war plan to Satan. Satan stuck out his chest and bragged that it would be no contest at all. Why? Because Satan believed that he could have taken the allegiance of all of God's angels in Heaven, given enough time, and now, he believed he could take the allegiance of all human beings on planet earth for himself. Satan would get all of them and God would get none of them. God once again disagreed with Satan and told him- not so, Satan, I will have a few people on planet earth who will choose to love Me for who I Am. Remember, that God always deals with a remnant or just a few. Satan would only agree to this test of mankind with one stipulation- that he would be allowed by God to come before Him in Heaven as a visitor to slander any individual on earth who dared to love God for Himself. God agreed. But God also had one stipulation- that He would come to earth as a human being in His own timing. Satan agreed. So, Satan went out and was able to test the majority of mankind NOT to love God or to serve Him. But, God, was right also. He had a remnant of people who did love Him for who He was. Now, you know why there are always more spiritually unsaved folks than saved folks on this earth.

God may have had another goal in mind as well- God wanted to eventually replace the number of angels (one third in symbolism) that he lost to Satan (in the war in Heaven) with human beings who loved God for who He was. This entire plan was organized and agreed to in Heaven before modern mankind was created.

Satan and his imps were on planet earth when Adam and Eve were created. Satan studied them very carefully. They literally visited with God every day so Satan had to be very crafty on how to get them to be disobedient to God. So, Satan (as recorded in Genesis) deceived Eve to sin with the use of a lie. It worked. Adam and Eve's disobedience to God really hurt God. This resulted in a great victory for Satan. He claimed ownership of Adam and Eve and bragged it all over Heaven that he turned 100% of all mankind against God. God, he said, failed at His own test! All of that caused a lot of problems for God. It appeared that God lost face and it looked like God's plan was a failure. This failure of mankind is known in theology as the Fall of Mankind.

This warfare on planet earth, involving human beings, was going to be a life and death struggle. It would be vicious involving a lot of death, pain, and suffering. Every human being born on this earth would be embroiled somehow in this spiritual warfare one way or another.

So, how can that be relevant to you and I? Satan claims ownership of you and I and he does not want God to own us. He can legally claim that based upon the fall of mankind when mankind transferred its authority to Satan. That means that Satan has justification to claim that every person on earth belongs to him by default. But God created us with free will- meaning that the choice of who owns us is up to us. You and I can choose to serve God and break Satan's ownership of us. Jesus Christ came to give us the power to do so. I made the decision many years ago to let Jesus Christ own me. I encourage you to do the same thing now. That is why evangelism is so important. We must tell the unsaved peoples of this world they are slaves to sin, owned by Satan, and in a lost spiritual condition. We must tell them about Jesus Christ and how His blood cleanses from all sin. How accepting Him transfers their ownership from Satan to Christ with a new inner nature that is Christ-like. And how Christ will give them power to live a Christian life and to withstand the persecution that Satan will instigate.