St Paul speaking to the Hebrews to encourage them:
God is portrayed as a parent who loves us – he disciplines us / suffering to get us on the right path. He forgives us / grace .
The old covenant / 10 commandments was all about discipline with no grace and no way could we keep the 10 commandments all the time – so we are all sinners.
The new convenant add forgives / grace – very important.
When we fall short of God’s will, we can expect Him to “discipline” us, the same way a loving father corrects a wayward child. That chastening is not a sign of hate—it’s proof that the Father loves us enough to pull us back towards the right path.
A comparison is made between the manner in which the old covenant was introduced – reasonable fear,
as opposed to how we perceive the new covenant offers us peace and security, and very importantly grace; this is the only way we can be members of “a kingdom that cannot be shaken”