17 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.
This verse introduces the theme of the inheritance of the believer. The idea of inheritance flows out of the idea of sonship in the previous verses. Children by inference receive inheritance from their parents. An heir is someone who receives property or value from someone else.
17 and if [since] children,
Since Christians are “children” of God, they inherit prerogatives from God. This is a fulfilled condition in our souls from God; it is no possibility but rather a fact. The Holy Spirit bears testimony with our spirit that we belong to God’s family.
then heirs—heirs of God
An heir is someone who receives an allotted possession by right of sonship. Christian heirship does not depend on the death of a progenitor. Christians share their inheritance with the One who never dies. All Christians will share Christ’s inheritance.
Earthly children inherit their parents’ estate. Each sibling is an heir, and the other siblings are co-heirs. Here Christians have a spiritual heritage from God. The source of this heritage is God Himself. It is His to give. He is not only the source of our inheritance, but He Himself is our inheritance.
Ps 73: 25 Whom have I in heaven but You? And there is none upon earth that I desire besides You.
Lam 3: 24 “The Lord is my portion,” says my soul, “Therefore I hope in Him!”
and joint heirs [co-heirs] with Christ,
Christians are co-heirs with Christ. We inherit His spiritual blessings. We are heirs by virtue of being joint-heirs with Christ. We cannot receive this inheritance apart from Christ. Our inheritance comes from our union with Christ in positional truth.
There is a difference between an heir and a joint-heir. A joint-heir means that each individual owns the whole. If a businessman dies and leaves the entire company to his three sons, all three sons fall heir to the entire company. The company in this case is not divided into three parts. Thus, everything that the Father gave to Christ is ours as joint-heirs with Him.
Our spiritual position is a guarantee of our heredity.
The assurance of Christians always has to do with positional truth. Christ is the heir of all things (He 1:2). Since heirship is based on sonship and we are identified with Christ in His heirship, this positional heirship demands that the Christian has eternal life.
Titus 3: 7 that having been justified by His grace we should become heirs according to the hope of eternal life.
Heirship thus means that believers share the destiny of Christ (Ep 1:11). This heirship is based on election (He 9:15) and grace (Ga 3:29). Heirship results in eternal security (1 Pe 1:4,5). The indwelling of the Holy Spirit is the down payment for the inheritance of that eternal security (Ep 1:14).