Romans 8:11-20
Rom 8:11 (KJV)
But if the Spirit of him that raised up Jesus from the dead dwell in you, he that raised up Christ from the dead shall also quicken your mortal bodies by his Spirit that dwelleth in you.

Here is a great promise to every true believer. God the Father, who raised the Lord Jesus Christ from the dead, will, on the last day, quicken or make alive our physical bodies, whether we have already physically died or we are still living in them on the last day. God is going to make the believer fit to live in Heaven, a place of total righteousness. As we are now, the physical body would not be able to survive the glory of God the Father and God the Son. This is why on the Mount of Transfiguration, Peter, James, and John had to be temporarily qualified to be able to see the Lord Jesus in His glory. If they were not qualified, then they would have been consumed as straw in molten lava.
(Mat 17:1-2 KJV) And after six days Jesus taketh Peter, James, and John his brother, and bringeth them up into an high mountain apart, {2} And was transfigured before them: and his face did shine as the sun, and his raiment was white as the light. How long could you look at the sun without protection before you went blind? It is the same principle as a human trying to look on the Glory of God. This is why when Moses wanted to see the Glory of God, God himself shielded the eyes of Moses. (Ex. 33:18-23)

Rom 8:12 (KJV)
Therefore, brethren, we are debtors, not to the flesh, to live after the flesh.

Based upon what Paul just said, we are not debtors to the flesh to live after or according to the flesh but we are debtors unto God who is the one that is going to quicken the mortal body into an eternal spiritual body. We owe nothing to the flesh but because of all the work that God has done in our body, it is Him that we are indebted to.
(Eph 4:30 KJV) And grieve not the holy Spirit of God, whereby ye are sealed unto the day of redemption. Whenever we sin, we grieve the Holy Spirit who dwells in us and that is why we are never to think that we owe a debt to the flesh and to indulge ourselves in sinful activity.

Rom 8:13 (KJV)
For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live.

Now Paul is exhorting the believers that if they live a life of flesh, then they can expect to die from that life. Now a true believer cannot lose their salvation but they are susceptible to the same physical penalties of living sinfully as unbelievers are. Let us take an example from someone who works seven days and never rests. It does not matter if the person is a believer or not, they will suffer physical penalties for such a life. A person who smokes or drinks alcohol will suffer from the sicknesses associated with these worldly habits and it does not matter if a person is saved or not.
(Rom 13:14 KJV) But put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lusts thereof. The true believer is to avoid the ways of the world by not re-igniting the passions of sin which were killed by the sacrifice of Christ. If we are dead to sin, we must keep them mortified or dead, for if we resurrect those sins of the old man. It could be our downfall right to the grave and with it goes our testimony.

Rom 8:14 (KJV)
For as many as are led by the Spirit of God, they are the sons of God.

The Christian is led of the Holy Spirit as part of their normal Christian walk. I remember in 1990 I attended a “Deeper Life Seminar” at the Seminary where I worked and taught and Dr. Norman Wilson of the Wesleyan Hour was the main speaker. I will always remember his opening comments, “Instead of calling it a deeper life seminar, we should call it the ‘Normal Life Seminar.’” He is absolutely correct. The Christian who is indwelt by the Holy Spirit will be led by the Spirit. The word “led” in the Greek is in the Passive Voice which means the Holy Spirit is doing the leading and not the Christian. The Christian is the recipient of the guidance of the Holy Spirit. This verse tells us that those who are led by the Spirit of God are the regenerated sons of God because the Holy Spirit does not dwell in the hearts of the unsaved.

Rom 8:15 (KJV)
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.

(Heb 2:14-15 KJV) Forasmuch then as the children are partakers of flesh and blood, he also himself likewise took part of the same; that through death he might destroy him that had the power of death, that is, the devil; {15} And deliver them who through fear of death were all their lifetime subject to bondage. When we were unsaved we were in the bondage of the Law which consistently kept the eternal death penalty over us. Physical death is also feared by unbelievers since they do not know what is on the other side and that is why they are in bondage to the fear of death. Physical death to the believer is the beginning of eternal life in Glory. (Gal 4:9 KJV) But now, after that ye have known God, or rather are known of God, how turn ye again to the weak and beggarly elements, whereunto ye desire again to be in bondage? The Christian is not indwelled with the spirit of bondage that we had when we were unbelievers. Instead we have received the Spirit of adoption. This means, that because of the indwelling of the Holy Spirit, we were taken out of the kingdom of Satan and transplanted into the Kingdom of God and that transference is so thorough, that we are able to see God in a relationship so close that we can call Him “Daddy,” which is what “Abba” means.

Rom 8:16 (KJV)
The Spirit itself beareth witness with our spirit, that we are the children of God:

The Holy Spirit bears witness that we are saved. The fact that we are indwelled by the Holy Spirit, gives us a kinship to other believers which we can identify with. There are many out there who claim to be saved by reason of Church membership but instantly you can tell of what spirit they are by what their priorities are. If you go to a church and hear a speaker talking about environmental issues, you will not identify with them on a spiritual level but if a missionary speaker was speaking about reaching certain people groups, your spirit will identify with the ministry desire of that person. In this verse, we read the term “Spirit itself.” This phrase has been used by cults such as the Jehovah’s Witnesses to try and prove that the Holy Spirit is only a force and not a person. Here is where their understanding hits a dead spot. The word “itself” is in the neuter gender, which means that it is neither male nor female. Spirit does not have a sexual category, therefore the word “itself” is a very good word to describe the Holy Spirit.
(Mat 22:30 KJV) For in the resurrection they neither marry, nor are given in marriage, but are as the angels of God in heaven. Angels are spirit and that is what the believers will be like in Heaven.

Rom 8:17 (KJV)
And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.

Since we are children of God by means of the indwelling of the Holy Spirit, the benefits of salvation do not end there. We are also heirs of God. Remember back in verse 15 we read that we were adopted? Well that adoption into the family of God makes us co-heirs with Christ and carries with it all the benefits of spiritual adoption.
(Heb 1:1-2 KJV) God, who at sundry times and in divers manners spake in time past unto the fathers by the prophets, {2} Hath in these last days spoken unto us by his Son, whom he hath appointed heir of all things, by whom also he made the worlds; We read that Christ is the heir of all things and since we partook in his sufferings by means of imputation, we will also be glorified together with Christ, not on the same level since He is eternal God, but His glory will also be imputed to the believer on some level.

Rom 8:18 (KJV)
For I reckon that the sufferings of this present time are not worthy to be compared with the glory which shall be revealed in us.

Here is a great principle in that even though we may be going through a rough time now, whether it be persecution, sickness, or something else, these sufferings in no way can ever be compared to the ultimate glory which shall be revealed in us. Remember, our bodies are tied to this world and are susceptible to all kinds of pain and suffering but the redeemed soul that we possess can never be touched by the things on this Earth. The soul, which has been redeemed will be glorified in our new glorified bodies which the Lord will give us on the last day. Those glorified bodies could never be compared to the frail, corrupted flesh which we now possess. In fact, the only bit of insight we have on the spiritual body in its glorified state is what is revealed to us on the Mount of Transfiguration. (Matthew 17:1-9)

Rom 8:19 (KJV)
For the earnest expectation of the creature waiteth for the manifestation of the sons of God.

Here we see in view that these creatures are desiring to see the manifesting of the sons of God, that is, in their glorified state in the New Heaven and New Earth. These creatures may be the ministering angels, it may be the creation of the world itself and all it contains or it can be the Christians themselves who look forward to the last day when God is going to give all His children their glorified spiritual bodies. The word “manifestation” carries with it the meaning of “revealing or unveiling.” Right now as God is saving His Elect, the world and our physical bodies remains in decay but as soon as the last one becomes saved, then He will turn our vile bodies into glorified ones.
(Phil 3:21 KJV) Who shall change our vile body, that it may be fashioned like unto his glorious body, according to the working whereby he is able even to subdue all things unto himself.

Rom 8:20 (KJV)
For the creature was made subject to vanity, not willingly, but by reason of him who hath subjected the same in hope,

Not only were human beings made subject to vanity but the entire creation was plunged into vanity. The word “vanity” in the Greek carries with it the idea of “futility or worthlessness.” The entire creation was plunged into a state hostile to God because of sin and this punishment was placed on the entire creation. One need only look at a garden with weeds and bugs that devour it, storms like hurricanes and tornadoes, hatred built up between humans, etc. The entire creation has turned against itself because of sin. The animals did not sin against God yet they were also subjected to the same situation. In the beginning, the animals were herbivorous but since sin came on the scene, many of them became carnivorous and vicious. Since animals do not have souls and are only tied to this earth, the hope that we now look for is the hope of the second coming of the Lord Jesus Christ when God shall create the new Heavens and the New Earth where only righteousness dwells.
(2 Pet 3:13 KJV) Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness.