Based on Hebrews 1:2 where the writer says IN THE LAST DAYS God has spoken to us through the son, when are the last days?
In order to understand what is meant by “the last days” we need only quote Hebrews 1:1-2a. They read, “God, after He spoke LONG AGO to the fathers in the prophets in many portions and in many ways, in THESE LAST DAYS has spoken to us in His Son” (NASB). The phrase “long ago” obviously refers to Old Testament times when God was speaking to “the fathers” (Abraham, Isaac and Jacob and thus the whole nation of Israel) by “the prophets.” His revelation to them was PARTIAL. In contrast, the phrase “the last days” refers to the coming of God’s only begotten Son into the world and God’s FULL REVELATION of Himself through “His Son.” During Old Testament times God was slowly revealing Himself to one nation in various ways, but now God has given Israel and the whole world a complete revelation of Himself in His blessed Son.
How has God spoken to us in His Son? Let’s read John 1:14 & 18, “And the Word became flesh and dwelt among us, and we beheld His glory, the glory of the only begotten of the Father, full of grace and truth…No one has seen God at any time. The only Son, who is in the bosom of the Father, He has declared Him.” In was through the Son of God’s Incarnation that God has revealed Himself to mankind. From the manger to the cross Jesus Christ revealed (in everything He did and said) God’s love and holiness. When people saw the Lord Jesus, they were also seeing the Father! You may recall Philip saying to Jesus, “Lord, show us the Father” (John 14:8). Jesus responded by saying, “Have I been so long with you, and yet you have not come to know Me, Philip? He who has seen Me has seen the Father” (verse 9). This does NOT mean that they are the SAME PERSON; it means that they are BOTH GOD and they have the SAME NATURE. This is what is meant by Jesus’ words in John 10:30, “I and the Father are one.”
I would only add one more thought. Though “the last days” began with the Incarnation of the Son of God, they will continue throughout this present age (the “Church Age”). The Lord’s revelation of the Father was limited to 33 some years while He walked among men in the land of Israel, yet God saw fit to inspire men to write down, in the sacred scriptures (i.e. the New Testament), the truth about His Son. In these blessed scriptures God has also “spoken to us in His Son.” (308.4) (DO)