Essan: "But Saul was God's chosen representative. The Society isn't."
First of all, you are confusing "god" with your true Creator. God is an entity created by man. Even the bible scriptures show you that gods are many.
If Saul was "God's chosen representative" then this 'god' was most probably a cabal of leaders or a headship of such.
David did not recognize nor acknowledge Saul as having any spiritual authority over him. David did not capitulate to Saul's dictates.
If you remember he refused to eat the (spiritual) food served at Saul's table. Although the scriptures may use the allusion that David did not eat meat at the King's table, this is actually a thinly disguised metaphor meaning that the "meat" or "heart" of Saul's philosophies, morals, dictates were not in line with David's being true to his own conscience. This is why David refused to partake of the "table" of Saul.
David set himself apart from whatever evil and erroneous teachings that Saul promoted.