When God separated Abraham and his family from his family and his country, and when God separated Israel from Egypt, their sanctification was also geographical. He literally moved them from one place on earth to another. His purpose was to establish a new community of people all involved in the same purpose.
With the church, our separation is not geographical but spiritual, moral, and ethical, while still living geographically within the system that we were born into. We must become separated from the way, from the manner, from the lifestyle, from the attitudes of the system that we were born into and moved (motivated) to make God's way, His manner, His system, His attitudes ours. That is how we "come out" of Babylon.
Abraham and Israel literally moved geographically. Some of us may move geographically, but that is not really what God has in mind. He desires a spiritual, moral, ethical, and attitudinal departure from our friends, neighbors, family, the gang we ran with, or whatever. We are called to be different.
The concept of God's separating, making holy, and establishing a new community, is not lost. The community aspect is merely reserved until a later time. Under the New Covenant, the community is the Kingdom of God. It is a goal we are moving toward as He prepares His set-apart people to enter that new community.
So where are we headed? To the Kingdom of God. Are we headed there geographically? No. We stay right where we are, but we still "come out" of Babylon in a spiritual sense. We are still sanctified by a change of attitude, of practice, and of conduct. Instead of immoral, we become moral. Instead of being unethical, we become ethical. Instead of being spiritually anti-God as Satan is, we become spiritual in the way God is spiritual.
That is how we "come out." We are set apart for that purpose. At this time, geography has little or no part in the sanctifcation of the overwhelming majority of God's people.
John W. Ritenbaugh
Sanctification and Holiness (Part 1)