What force could cause Lucifer, Adam, and Eve to deviate from God's Principle and turn away from His love?
Only one force is stronger than the Principle: love. God made the power of love so absolute that even His Principle does not preclude expressing love in a way that violates God's will.
No one would choose death merely to eat a fruit. The force of love, however, can blind people and drive them even to death. God created man and woman as objects to whom He could send His limitless love and from whom He could receive a full response of love.
God wants us to live in the fullest expression of love and enjoy complete happiness on earth and hereafter. If the Principle controlled our love, then love could not be absolute.
After reaching the state of Perfection, we are no longer under the Principle but under the Direct Dominion of God's love. Perfect freedom and happiness do not exist under the Principle, but only in the dominion of God's absolute love.
Since God made the power of love so great, Lucifer, Adam, and Eve could transgress the Principle through their misuse of love. In the Direct Dominion of God, our unconditional love of God and God's infinite love toward us form such a powerful bond that no other love can separate us from God.
However, before we reach Perfection, our love for God is incomplete and may be misdirected. For this reason, man and woman should experience a full union of love with each other only after their love for God has become unconditional.
Thus we see in Genesis, "You may freely eat of every tree of the garden; but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall die." (Gen. 2:17)
In this way, they were directed to center their love on God, not on themselves.