How are we heirs of GOD

(I have condensed verses from Galatians 4 for brevity but I encourage you to read the whole chapter about four times so that you get the fuller meaning of what it is saying)

Gal 4:1
... Child differs not from a servant though he be lord of all.
:4
... when the fullness of time was come...
:5
To redeem them...that we might receive the adoption of sons.
:6
... crying Abba, Father... in our hearts
:7
... no more a servant, but a son...
... an heir of God through Christ

We are heirs of God throught Christ!
Without Christ we are not heirs/sons/daughters of God.

Christ is an active, mandatory part of the transaction/agreement/contract between us and God that enabales us to be heirs of God and as such to access His power to enable us to do what He asks of us.

Therefore, we need His Holy Spirit before any of this can work. The Holy Spirit is the spirit of adoption.

Romans 8:15  For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father.