Why are we to act different than the Word? Leviticus 19-21

Leviticus 20:22-26 (NASBStr)

‘You are therefore to keep all My statutes and all My ordinances and do them, so that the land to which I am bringing you to live will not spew you out. Moreover, you shall not follow the customs of the nation which I will drive out before you, for they did all these things, and therefore I have abhorred them. Hence I have said to you, “ You are to possess their land, and I Myself will give it to you to possess it, a land flowing with milk and honey.” I am the Lord your God, who has separated you from the peoples. You are therefore to make a distinction between the clean animal and the unclean, and between the unclean bird and the clean; and you shall not make yourselves detestable by animal or by bird or by anything that creeps on the ground, which I have separated for you as unclean. Thus you are to be holy to Me, for I the Lord am holy; and I have set you apart from the peoples to be Mine.

In the above passage God gives Moses the reason for all the ordinances and commands in the previous few chapters.  God has given them instructions about sexual misconduct, how to treat the poor, how to avoid idolatry, and many more commands.  Throughout the book of Leviticus God gives them a command and then states, "For I am The Lord," or, a divergence of that.  In the above passage He gets even more explicit.  He tells them that the reason for this type of conduct is that they are to be different than the world around them and that the world around them was being condemned because they did not reflect the glory and character of God.   The point being made is that how we treat others shows the character of God within us.   God is giving us the motivation and the mission all rolled into one.  We are to be separate from the world in conduct because He is Holy.  Our conduct reflects His holiness ... or, should.   We ought not act as though we are like the world, when, in essence we are His children and therefore different than the world.   The children of the king do not act (or, should not) like the children of the pedestrian.   We ought not to act as though we are "better" than they are, but we ought to act as though we are reflecting our Father in Heaven.  He is perfect and holy and we are His children.  Act like it.