What is John saying in Luke Chapter 3?

i’ve never really been able to make sense of what John is preaching in Luke chapter 3 verse seven through nine

Here he says “You brood of vipers! Who warned you to flee from the wrath to come? Bear fruits i keeping with repentance and do not begin to say to yourselves, We have Ahbraham as our father. For I tell you, God is able from these stones to raise up children for Ahbraham. Even now the axe is laid to the root of the trees. Every tree, therefore that does not bear a good fruit is cut down and throw thrown into the fire.”

Obviously, this is about repentance, but I don’t really understand what the wrath bit is about if Jesus is coming to die for our sins etc. Why does he call them a brood vipers?