Compare Nehemiah 9:20 and Exodus 23:20-22
20 You gave your good Spirit to instruct them. You did not withhold your manna from their mouths, and you gave them water for their thirst.
Nehemiah 9:20 NIV
20 “See, I am sending an angel ahead of you to guard you along the way and to bring you to the place I have prepared. 21 Pay attention to him and listen to what he says. Do not rebel against him; he will not forgive your rebellion, since my Name is in him. 22 If you listen carefully to what he says and do all that I say, I will be an enemy to your enemies and will oppose those who oppose you.
Exodus 23:20-22 NIV
There can be little doubt that the Holy Spirit and the Angel of Yahweh are one and the same and that the Holy Spirit is an angel. However, He is not merely an angel. He is the Angel. The firstborn over all creation and the other angels were created through Him.
In Biblical thinking an angel and a spirit seem to be the same thing. When Peter is miraculously freed from prison in Acts 12 and knocked at the door of Mary the mother of John, the disciples did not believe it was him, but thought that it was his angel:
12 When this had dawned on him, he went to the house of Mary the mother of John, also called Mark, where many people had gathered and were praying. 13 Peter knocked at the outer entrance, and a servant named Rhoda came to answer the door. 14 When she recognized Peter’s voice, she was so overjoyed she ran back without opening it and exclaimed, “Peter is at the door!”
15 “You’re out of your mind,” they told her. When she kept insisting that it was so, they said, “It must be his angel.”
Acts 12:12-15 NIV
The meaning here seems to be that the disciples thought that Peter had been executed in prison and that it was Peter’s spirit who was at the door. I guess another word for it is the word ‘ghost’. The disciples thought that Rhoda was seeing Peter’s ghost. Interestingly, the Holy Spirit is also referred to as the Holy Ghost. Therefore, the words ‘angel’, ‘spirit’ and ‘ghost’ seem to be synonymous.
