Chapters 12-14 deal with service for G-d and G-d's righteousness displayed:
Romans 12:1 I urge you therefore, brethren, by the mercies of G-d, to present your bodies a living and holy sacrifice, acceptable to G-d, which is your spiritual service of worship.
Paul is talking to believers here.
Paul begs us through the mercy of G-d that we present our bodies for living service. Our minds are renewed through the power of Ruach HaKodesh (the Spirit) to follow the will of the Father. Yeshua is our example and focus.
Just as Ruach HaKodesh dwelt in the "Holy of Holies" of the Temple, today He dwells in the body of each believer. This is truly mind-boggling. This is ONLY possible because of the shed blood of Yeshua being applied to the doorposts of our hearts. His blood makes our temples of our bodies whiter than snow. It is for this reason that we must take care of our bodies, not polluting it with the things of this world.
See our study on the Tabernacle for more information.
The Spirit is separate from the brain or body. Our thoughts are on the Spiritual fruit.
Romans 8:16The Spirit itself bears witness with our spirit, that we are the children of HaShem:
With this Spirit come gifts to all, which we are not to compare to one another. We should complement one another not compete with each other.
Romans 12:2-3 And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what the will of G-d is, that which is good and acceptable and perfect. For through the grace given to me I say to every man among you not to think more highly of himself than he ought to think; but to think so as to have sound judgment, as G-d has allotted to each a measure of faith.
We should not think of ourselves as being perfect or better than anyone else. If one measures by their own standards this leads to a superiority complex. If one measures by the standards of others this leads to an inferiority complex.
Faith (trust) teaches that we are sinners, but we receive mercy. Faith (trust) teaches we are not always who we think we are. We are neither superior nor inferior. Despite ourselves the Ruach HaKodesh will still use us.
We all have different gifts. Our mission is to find and test these gifts. We should make sure we do things that we are good at and not try to do things that we want to look good at but have no gift for.
Greek word for "gifts" is "Charismata" and can be translated as "grace" or "free gift".
Paul says through the grace (mercy) given to me.
Romans 12:4-5 For just as we have many members in one body and all the members do not have the same function, so we, who are many, are one body in Messiah (Christ), and individually members one of another.
We all work together as a body.
Romans 12:6 And since we have gifts that differ according to the grace given to us, let each exercise them accordingly: if prophecy, according to the proportion of his faith;
Gifts - Prophecy - This is not a prediction but can be any message from G-d. It instructs and improves believers. It requires an equal amount of faith on our part.
Romans 12:7 if service, in his serving; or he who teaches, in his teaching;
Ministry - acts of service for others. Some refer to this as the gift of helps.
Teaching - some are given the gift of teaching others the word of G-d.
Romans 12:8 or he who exhorts, in his exhortation; he who gives, with liberality; he who leads, with diligence; he who shows mercy, with cheerfulness.
Exhortation - Greek word paraklesis "a calling near" means comfort.
Gives with liberality - some have the supernatural gift of giving.
Leads, with diligence - leadership and administration.
Mercy with cheerfulness - acts of kindness.