Romans 8:17

“Now if we are children, then we are heirs – heirs of God and co-heirs with Christ, if indeed we share in His sufferings in order that we may also share in His glory.”

Receiving an inheritance is yet another benefit of being a child of a family. Normally an inheritance is passed on after the father dies; however in God’s case, because He cannot die, He grants the inheritance when the old world passes away and all is created anew.
When we stop and think about it, this is an amazing Scripture. We, sinful, pathetic humans, who were drawn to God by the Spirit, can become co-heirs with Jesus Christ, the Son of God. Jesus has been promised the earth and the nations as His inheritance (Ps. 2:8). He promises that we will get to sit on His throne and reign over the earth with Him (Rev. 3:21). He shares all of this with us, the Church, as His bride.
We are co-heirs, Paul says, “if we share in His sufferings”. I don’t believe this is referring to us only receiving an inheritance if we suffer for the sake of the gospel, if we are persecuted or martyred for our faith. Rather, sharing in Christ’s sufferings means to appropriate His death on the cross to our lives. We are saved by faith in Him, that His death was sufficient to pay the penalty for our sins. Thus we identify ourselves with Christ. Similarly we share in His glory. We do not detract from the glory of Christ, nor are we granted any glory of our own because of our works, for instance. Rather, we reflect His glory, and our presence there shows the power of His sacrifice, and brings glory to Him.