God created man in His spiritual image, and He relates to and fellowships with man through man’s spirit (Gen 1:26, Rom 8:8, John 4:24).
All the characters mentioned in the scriptures—from the judges and kings to the prophets and disciples—are not referred to or identified by the scriptures as their human bodies, but as their spirits.
Let us look at Moses as an example. In the books of Exodus and Ezekiel, God spoke to Moses about Pharaoh, and at Mount Sinai, He spoke to him about the Ten Commandments (Exodus 10:1, Exodus 19:20). The Lord was fellowshipping and talking to Moses through Moses’ spirit. Similarly,
When God appeared to Elijah and spoke to him, He was relating to Elijah’s spirit (1 Kings 17-19). There are many more examples, though time does not permit me to mention every prophet, king, and disciple.
Furthermore, when Jesus took Peter, James, and John up a high mountain by themselves, Moses and Elijah appeared and talked with Him (Matthew 17:1, Mat 17:3). The bodies of Moses and Elijah had been buried about 4,000 years before they appeared with Jesus, yet the scripture still referred to them as Moses and Elijah.
We must be able to identify our human spirit in union with the spirit of Jesus through the power of the Holy Spirit. We must also be able to separate our human spirit from our soul and body to be able to successfully work according to the Spirit (Gal 2:20, 1 Cor 3:16, Gal 5:17).