The writer of Hebrews identifies three phases of Christ’s ministry:

1. Past Appearance - “He has appeared once for all at the culmination of the ages to do away with sin by the sacrifice of himself.”
2. Presently Appearing – “He entered heaven itself, now to appear for us in God’s presence.”
3. Future Appearance – “He will appear a second time…to bring salvation.”

His first appearance came “at the culmination of the ages.” This phase is synonymous with Paul’s phase “ends of the ages” in First Corinthians 10:11 and Galatians 4:4, and Peter’s “end of the times”
in First Peter 1:20. Here in Hebrews “the culmination of the ages” seems to be speaking, along with Paul’s “ends of the ages” and Peter’s “end of the times,” about the culmination of the Old Testament age which includes the age of the Levitical priesthood, the age of the earthly tabernacle/temple, the Law of Moses, etc. This would mean the time that follows this passing age would be a new age.
This new age is the church age of today which places Christ in heaven serving in the real temple where he appears before God for believers during their time on earth. But, even this church age will pass when Christ appears a “second time” on earth “to bring salvation to those who are waiting for him.”

The Greek word for "salvation" referred to deliverance from things like war, a storm, disease, an
enemy or traveling difficulties. In the New Testament "salvation" speaks of deliverance from sin and God’s coming wrath. Isaiah speaks of both of these salvations. The first is the deliverance from sin spoken of in Romans 5:1, 6, 8 which matches Isaiah’s words about the Messiah’s first appearance:

                “He makes himself an offering for sin…He bore the sin of many.” – Isaiah 53:10, 12

The second deliverance is from God’s wrath spoken of in First Thessalonians 1:10, and also,
Romans 5:9. This is found in Isaiah’s words concerning the Messiah’s second appearing and the
salvation, or deliverance, that will take place at that time:

ISAIAH: “Who is this, robed in splendor, striding forward in the greatness of his strength?
MESSIAH: “It is I, speaking in righteousness, mighty to save.”
ISAIAH: Why are your garments red, like those of one treading the winepress?
MESSIAH: “I have trodden the winepress alone; from the nations no one was with me. I trampled them in my anger and trod them down in my wrath; their blood spattered my garments, and I stained all my clothing.

"The one who retains the rule of the truth received through baptism unchangeable in his heart will surely recognize the names, the expressions, and the parables taken from the Scriptures [by the gnostics] but will by no means acknowledge the blasphemous use which these men make of them."
- Irenaeus, 184 AD