Read Romans 15.
Paul's instructions about accepting one another began at the end of chapter 12 and continue into this chapter. We are to "Love one another with brotherly affection. Outdo one another in showing honor" (12:9-10). But what happens when there is a disagreement on a non-essential opinion? The essentials would certainly include what is the Bible, who is Jesus, and how is a person saved from their sin. Each person coming into the local church family brings personal experiences, individual preferences, and differing levels of spiritual maturity.
To simply the understanding, two categories of spiritual growth are mentioned from chapter 14 and into chapter 15: the weak and the strong. Some may consider certain foods, celebrations, etc. to have importance that others do not. The point in chapter 14 is that each individual must do whatever they do "in honor of the Lord" (14:6) and with complete confidence that they are pleasing God in that conviction (14:23). If we are not allowed to quarrel about varying opinions in the church (14:1), what are we to do? How can we truly accept one another when there are some obvious differences?
"We who are strong (Greek=capable) have an obligation to bear with the failings (Greek=inabilities) of the weak, and not to please ourselves." A person new to the faith, or one with differing views, may lack the experience, teaching, or ability to appreciate a certain non-essential issue as others do. The strong are those with a broader understanding and experience to be able to "pursue what makes for peace and for mutual upbuilding" (14:19). Since the "weak" are not able to do so, it is the responsibility of the "strong" to bear with, endure, and help others to protect unity in the church. It is an opportunity for the "weak" to begin to mature as the "strong" exercise loving acceptance in the process.
No little humility is required. This means serving each other's needs more than our own. Why should we lay aside our rights for the sake of others? Now, Paul presents the supreme example--because that is how Christ treats us. If Jesus had held on to His rights, He would have never left heaven in the first place. At the Last Supper, it was Jesus who took upon Himself the role of a servant and washed the disciples' feet (John 13) and said, "I have given you an example."
There are only two places in the Bible where Christ is called our example. In John 13, Jesus is our example of servanthood and, in 1 Peter 2:21, He is our example in suffering. Both of those can cause great abrasions to our human instinct of self-protection. But they are part of our calling in Christ.
Therefore, we are "to live in such harmony with one another...and welcome one another as Christ has welcomed you, for the glory of God." (15:5 and 7).