“The Spirit Himself bears witness with our spirit that we are children of God, and if children then heirs—heirs of God and joint heirs with Christ, if indeed we suffer with Him, that we may also be glorified together” Romans 8:16-18
When you give your life to Christ you are adopted into the family of God. Everyone was born through Adam, we are sons of Adam until we give our life to Christ, then we no longer belong to the lineage of Adam, but we are adopted by the spirit into the lineage of Jesus Christ making us children of God.
We become heirs of God and joint heirs with Christ. An heir receives all the things promised by the heiress. When the Bible says we are joint heirs with Jesus it means we receive ALL the things Jesus receives as the son of God.
The condition is if we suffer with Christ. What does it mean to suffer with Christ?
To suffer with Christ means a conscious decision to follow the spirit and not the flesh. The flesh is pleasurable so when we suffer with Christ we die to ourselves and live for Christ. We share in His death and resurrection.
A Christian has a death when he gives his life to Christ he dies to the world. The promise as an heir is that when we die a self death, we also become resurrected and glorified together with Christ.
The present suffering of your life today cannot be compared to the glory which will be received in us, as heirs, of God. All the bad things u go through in life can never match the eternal glory we receive as Gods adopted children in His eternal family.
Give your life to Christ, submit yourself to the spirit of God and join Christ by dying to yourself and living for Jesus Christ as Gods adopted children.