What does sanctification really mean?
Sanctification means being set apart as different. Israel was mandated to be a set-apart nation of people, sanctified unto Jehovah, not supposed to be like the rest of the nations around them. It means being distinct from the pagan idolaters and not wanting to be like everybody else.
Les explains that sanctification is about being set apart. When God made His covenant first with Abraham and then with Moses and Israel, the first thing He mandated was that Israel be different—a set-apart nation of people, a sanctified people. They were not supposed to be like the rest of the nations. In 1 Samuel 8, the elders demanded a king so they could be like all the other nations. Samuel was heartbroken, but Jehovah told him to let the people have their way because they had rejected God, not Samuel. Israel knew the surrounding nations were pagan idolaters, and no one but Israel had a knowledge of the one true God.