God must have first priority in our lives.
One of the ways this is illustrated in the Old Testament is that the first of everything belongs to God. Jericho, the first city to be conquered when Israel entered the Promised Land, belonged entirely to God. Nothing in Jericho was to be taken or preserved. Achan’s sin was that he took what rightfully belonged to God.
When Israel moved against the city of Ai, the second city they conquered, the plunder of that city belonged to Israel.
At the end of the Old Testament, the Lord will ask incredulously: “Will a man rob God?” The answer is “yes,” for God accuses Israel of robbing him. They are not giving him first priority, and the priority they do give him is half-hearted.
Christians must ask themselves if they are really putting God first in their lives, and if they are, what is the evidence for that priority? If there’s little evidence, honesty demands we admit we’re robbing God. Faithfulness demands we change.