# Ahab behaved abhorrently by following idols
Possible meanings are 1) following the idols was in itself abhorrent behavior or 2) because he followed idols he engaged in other abhorrent behavior.
# removed before the people of Israel
"removed from the presence of the people of Israel" or "drove out of the land before the people of Israel". Here "Israel" refers to all twelve tribes of Israel and not just to the northern kingdom.