"Therefore," Paul concludes with almost certainty in Romans 15:7, "welcome one another as Christ welcomed you, for the glory of God." I believe this goes beyond welcoming our brethren in a church fellowship. It is rather an acceptance with a deep understanding of each other's sin-stained flesh and a full recognition that every one of us is at the mercy of our Lord.
What does Paul really mean when he said that we must welcome one another as Christ welcomed each one of us? Let us look back and see how were we accepted by Christ in His family.
1. Christ rejoices as we come to Him. At times, we require a lot of effort in joyously accepting our new family in Christ. Perhaps because of a past happened between you and your brethren, racial discrimination, unsettled issues, impressions and expectations. We must remember how God greatly values them in Luke 15:3-7 parable, where 99 others were left for one. It shows how Christ was 'infinitely pleased', as Matthew Henry puts it, in the repentance and conversion of great sinners. Matthew 10:40 also says "He who receives you, receives Me, and he who receives Me receives who sent me."
2. Christ looks at us impartially. Jews or Gentiles, the Lord did not show partiality among His chosen people (Romans 2:11). His promise is unequivocal. He welcomes those who fear Him and do what is right from every nation. James clearly spotted what every believer's attitude should be:
"My brothers, show no partiality as you hold the faith in our Lord Jesus Christ, the Lord of glory. For if a man wearing a gold ring and fine clothing comes into your assembly, and a poor man in shabby clothing also comes in, and if you pay attention to the one who wears the fine clothing and say, "You sit here in a good place," while you say to the poor man, "You stand over there," or, "Sit down at my feet," have you no then made distinctions among yourselves and become judges with evil thoughts? If you really fulfill the royal law according to the Scripture, "You shall love your neighbor as yourself," you are doing well. But if you show partiality, you are committing sin and are convicted by the law as transgressors." James 2:1-4, 8-9.
3. Christ redeemed us to the glory of God. Everything Jesus does is to His glory. His pleasure in saving us is to glorify Himself (Eph. 1:5-6 and Phil. 2:9-11). There is coherence on Paul's instruction to imitate Him as He imitates Christ. This is our chief end - to glorify God in every thing we do. "We receive each other in love and without judgment or condescension we do, as He did, to the glory of God" (J. MacArthur).
In wretched state, Christ welcomed us in His family. He demonstrated His love and mercy on the cross while we were still sinners. He brought light into our darkness and life in our death. We were accepted to glorify His name and in Him we will be glorified. God endured all our griefs and sorrows in his humanity to Calvary. He is patient in our weaknesses, even encourages us and will continue to do so until He comes again. May we always remember God's graciousness to us whenever we look at our brothers and sisters in Christ.
Source: John MacArthur New Testament Commentary on Romans