Peace and joy, in perfect submission to the will of Heaven, existed throughout the angelic host. Love to God was supreme, love for one another impartial. Such was the condition that existed for ages before the entrance of sin.—The Spirit of Prophecy 4:316, 317. TA 28.6
He [Lucifer] had a knowledge of the inestimable value of eternal riches that man did not possess. He had experienced the pure contentment, the peace, the exalted happiness and unalloyed joys, of the heavenly abode. He had realized, before his rebellion, the satisfaction of the full approval of God. He had had a full appreciation of the glory that enshrouded the Father, and knew that there was no limit to His power.—The Signs of the Times, August 4, 1887. TA 29.1
There was a time when ... it was his [Satan's] joy to execute the divine commands. His heart was filled with love and joy in serving his Creator.—The Signs of the Times, September 18, 1893. TA 29.2
Satan was a beautiful, exalted angel, and would have remained so forever had he not withdrawn his allegiance from God.—The Signs of the Times, December 21, 1891. TA 29.3