Summary: Most Christians identify themselves by affiliations or labels. We are Pastor so and so or Apostle so and so or we are Baptists, Methodists, Catholic, etc. The Bible doesn't use any of these to describe who we are in God's eyes.
DRAWN INTO THE FAMILY OF GOD
1. The mortification of sin (Romans 8:12-14)
Paul has just commented that “if Christ is in you the body is dead on account of sin” (Romans 8:10). And that “the Spirit of Him who raised up Jesus from the dead will also quicken (revivify, make alive) your mortal bodies by His Spirit who dwells in you” (Romans 8:11).
On account of this we have an obligation - a debt of gratitude - “not to live according to the flesh” but (by inference) according to the Spirit (Romans 8:12). This is a process known as ‘the mortification of sin in our bodies.’ This is a “putting to death” of sin - a handing it over to be executed (Romans 8:13).
Jesus was handed over into the hands of evil men, and crucified (Luke 24:7), and we are instructed to ‘take up the cross daily and follow Him’ (Luke 9:23). The execution of our fleshly nature has taken place (Galatians 5:24), but it is the responsibility of each of us to go on mortifying the misdeeds of the body. It is a life choice (Deuteronomy 30:19).
The only way to put our sins to death is through the empowering of the Holy Spirit (Romans 8:13), and by His leading (Romans 8:14). However, if we really are Christians, then the Holy Spirit has already taken up residence within us (Romans 8:9). This is a powerful resource, which we are obliged to tap into.
The idea of being “led by the Spirit” (Romans 8:14) is a yielding to His guidance. It may or may not include the idea of being ‘driven’ (Matthew 4:1; cf. Mark 1:12), but could be as tender an operation as removing the speck from your brother’s eye (Matthew 7:4). As the Holy Spirit enlightens us in relation to the sins which we commit, so He persuades us to deal with them - and our submission to His control is, in the final analysis, voluntary.
One of the proofs of our interest in this matter is a holy abhorrence toward sin, especially within ourselves. As we deal with this (Romans 8:13) we enter into the fullness that Jesus promises (John 10:10). It is only those who are led by the Spirit of God who are thus manifested to be “the sons of God” (Romans 8:14).
2. The witness of the Holy Spirit (Romans 8:15-17)
Not everybody receives Jesus, nor believes in His name (John 1:11-12). Our inclusion in the family of God is on account of our faith (Galatians 3:26). So - although Paul said elsewhere, quoting the Greek poets, ‘we are all His offspring’ (Acts 17:28) - it is not the so-called and somewhat overstated ‘universal Fatherhood of God’ that the Apostle is speaking about here.
As children of God we have been translated from an area of bondage to fear (Galatians 4:3), into the freedom of a loving relationship with God (Romans 8:15). In Roman times to be ‘adopted’ was to be brought into the father’s family to inherit his estate and perpetuate his name. We have, on this analogy, been hand-picked to bear the Father’s name and reproduce His character in our lives - not on account of any worthiness on our own part, but out of His love (1 John 3:1).
We have received the Spirit of adoption, whereby we cry: “Abba, Father” (Romans 8:15). This is a combination of the Aramaic and Greek words for ‘father’ and is a formula used by Jesus Himself when addressing God (Mark 14:36). The Cross stands between us and Gethsemane, and now we are enabled to address God in the same intimate manner (Galatians 4:6).
When we are thus enabled to pray, it is the Spirit Himself “bearing witness with our spirit, that we are the children of God” (Romans 8:16). This is the Holy Spirit’s ministry of inward assurance, whereby He has poured out the love of God in our hearts (Romans 5:5). The Holy Spirit gives us assurance of both God’s love, and our son-ship.
Paul also affirms that if we are the children of God then we are also heirs of God, and joint heirs with Christ (Romans 8:17). The Holy Spirit is the first fruits of our inheritance (Romans 8:23), the down-payment (Ephesians 1:13-14). Our inheritance is not only what God has to offer, but God Himself (1 John 3:2).
Jesus prayed that those whom the Father has given to Him will be with Him where He is, and behold His glory (John 17:24). The path to glory was not without its sufferings for Jesus (Luke 24:26). But if indeed we suffer with Him, we shall also be glorified together with Him (Romans 8:17).