When searching for a key that unlocks a mystery, note that Yahweh referred to the nation of Israel as an individual. In likeness, She referred to the holy Ghost Orders as individual;s.
Exodus 4:22 "Then you will say to Pharaoh: This is what the LORD says: Israel is My firstborn son."
We know from the Word that Israel was Yahweh's chosen people in that day and time. They were the reflection of what would become the Spiritual Israelites. Yahweh is ISRAEL and is LIGHT = Israelite. Understand? And so, the 144,000 are also spoken of as individuals, but are really a people making up the vast amount of Orders of holy ghosts serving Yahweh and Christ in the holy family.
Since Christ was Michael in his beginning, and Spiritual Israel rests upon his foundation - life sustaining blood Sacrifice, Yahweh was also correct in stating that Israel represented Her first born Son.
To know that Christ and Michael are the same, you need only unlock the mystery with the key of "firstborn." Michael was the firstborn creation of Yahweh, and the only direct creation. That in itself solves the mystery of whom Christ really was before coming to the earth to lay down his life and permit his blood to become the waters of life that flow back to Yahweh.
Revelation 7:4 "And I heard the number of those who were sealed: 144,000 sealed from every tribe of the sons of Israel:"
Here is the secret of the mystery. Every tribe represents Orders, and 144,000 represents individual Orders and not individual people. Each Order descended from the tribes of Israel and are named after 144,000 faithful servants of Yahweh from ancient Biblical time.
As people pass over to the other side, they are given the opportunity to hear the Truth and then cross over to Christ and Yahweh's side of the spiritual war. The excepts are criminals and evil doers that are punished. If a person refuses the invitation, they are converted to Satan's side. But those that cross on over become members of one of the 144,000 Orders of holy ghosts.
Ephesians 3:4 "By reading this you are able to understand my insight about the mystery of the Messiah." And not only that of Christ, but all mysteries of the Word.
"Souls under the Altar" defines that they are already saved and in Yahweh's protection by their status.
When I say "saved," I mean under oath to keep Yahweh's Laws and to serve Her throne as Christ being their HEAD, and thereby under Yahweh's protection and in no need of further deliverance from Satan's prison of Magog.
With the Word, one must use their insight to understand the meanings that put there in riddles.
"riddle1 >noun 1 a question or statement phrased so as to require ingenuity in finding its answer or meaning. 2 a puzzling person or... thing. >verb archaic speak in or pose riddles.
-DERIVATIVES riddler >noun.
-ORIGIN Old English, related to read."
Hosea 14:9 "Let whoever is wise understand these things, and whoever is insightful recognize them. For the ways of the LORD are right, and the righteous walk in them, but the rebellious stumble in them."