Because they are His identity. The Cross was always the point of Creation.
I agree.
Revelation 5:1-10 [NASB]
1 I saw in the right hand of Him who sat on the throne a book written inside and on the back, sealed up with seven seals. 2 And I saw a strong angel proclaiming with a loud voice, "Who is worthy to open the book and to break its seals?" 3 And no one in heaven or on the earth or under the earth was able to open the book or to look into it. 4 Then I [began] to weep greatly because no one was found worthy to open the book or to look into it; 5 and one of the elders said to me, "Stop weeping; behold, the Lion that is from the tribe of Judah, the Root of David, has overcome so as to open the book and its seven seals."
6 And I saw between the throne (with the four living creatures) and the elders a Lamb standing, as if slain, having seven horns and seven eyes, which are the seven Spirits of God, sent out into all the earth. 7 And He came and took the book out of the right hand of Him who sat on the throne. 8 When He had taken the book, the four living creatures and the twenty-four elders fell down before the Lamb, each one holding a harp and golden bowls full of incense, which are the prayers of the saints. 9 And they sang a new song, saying, "Worthy are You to take the book and to break its seals; for You were slain, and purchased for God with Your blood [men] from every tribe and tongue and people and nation. 10 "You have made them [to be] a kingdom and priests to our God; and they will reign upon the earth."