The book of Romans is a great doctrinal letter from the Lord. There is much meat to be digested in this book. None of it is too much for the born again Christian. It is necessary food for the child of God.
It is important for the true child of God to be fed a constant diet of good food. The Word of God is that good food. Recently I had a conversation with a person who was trying to defend his position on the local church. I have come across several who declare themselves to be obedient Christians, but they do not attend a true local church, nor are they members of a true local church. This particular person I spoke with defended his position in part by drawing from other men in history. This man proved his grave deficiency in spiritual matters. The Bible is the only and final authority for all true Christians. When we open it up to the Bible - plus, we have a major problem. Now we are open to the same problems that the Charismatics have. They claim their experiences have equal weight or maybe even superior weight to the Word of God. That of course is heresy. It is no different when a person tries to use the experiences of other people as being of equal value and even superior value to the Word of God.
The apostle Paul began chapter 12 with the call to action. The word translated as “beseech” means to admonish or to exhort. The authority is “the mercies of God”. The true child of God will respond to the mercy of God. The fraud will scoff at that and ignore it. God is gracious and merciful. He is also just and powerful. He gives man the opportunity to hear Him and to obey Him. He holds man accountable for his choices.
The context of chapter 12 is to born again Christians. Paul referred to them as “brethren”. Brethren are accountable to God. We need to present our bodies a living sacrifice, holy , acceptable unto God. Christians are not in a competition with other Christians. Christians are servants of the true God. When we understand this, it will make a big difference in our response to the Word of God. A true Christian is one who is visible. A true Christian does not have a secret spiritual life that is not reflected in his body. Christians do not get tattoos because they present their bodies holy and acceptable to God. Christians do not partake of drugs and alcohol for the same reason. They do not participate in the world’s music scene, etc. There are many things that Christians do not do because they are presenting their bodies as holy living sacrifices to God. We must be acceptable to Him. These examples are not a burden for the true child of God. The true child of God has already been changed by God. He is a new creature. He chooses to glorify God. Sin never glorifies God. The true child of God has no desire to sin. He will sin at times. He will also see the need to confess his sin to God and be forgiven and he will learn how to avoid yielding to that temptation.
Paul tells us this is our reasonable service. God is never unreasonable in His commands. He is always right.
In verse 2 we see that the true child of God needs to be humble. He needs to submit to God’s authority. He needs to choose to be transformed by the renewing of his mind. The world wants man to conform to its unrighteous standard. We are seeing that in recent times with the sodomite agenda. The world says it is hatred to speak the truth regarding this sinful lifestyle. The world says it is loving to accept all people for who they are and not try to change them. The problem with that is that the sodomite community expects others to change and accept them. Thus they are very one-sided in what they believe and demand. Sodomy is an abomination to God and to know this and be silent about it is hatred. To love someone is to seek to warn them of the consequences of sin and the blessing of turning to God in repentance and being saved.
The true child of God needs to be changed by the renewing of the mind. We renew our minds as we humbly submit to God’s Word. We cannot accept extra-biblical material as being equal to the Word of God. We must accept God’s Word as our only and final authority. False religions all have their “other” authorities. My background as a Mennonite, has its “church fathers”. The church fathers were fallible men at best and many of them were lost men. Even Menno Simons was not infallible. He was seeking to bring his followers into obedience to God’s Word. He was saved out of the Catholic false religion and he was growing in the truth as he studied God’s Word. Sadly, after his death, his followers did not heed his warnings and they built on a man rather than on God’s Word. Thus the Mennonites built on sand. They built on the writings of a man, rather than continuing to build on God’s Word.
God’s Word is good, acceptable, perfect. It is the will of God. We cannot know the will of God apart from His Word. He does not give us visions and dreams. He shows us in His Word what is right and what His child must follow.
In verse 3 we see that if we are proud we cannot grow. If we refuse to accept God’s Word as our authority, we cannot grow. If we want to pick and choose what we will believe, we cannot grow. James tells us that a double minded man is unstable in all his ways.
The true child of God needs to think soberly. When a child of God tries to defend himself with extra biblical material, he will realize just how foolish that is. He will be embarrassed to think that he stooped to such a low standard.
God shows us in His Word that we as people are all fallible. The apostle Paul stated:

I Corinthians 11:1 Be ye followers of me, even as I also am of Christ.