Paul mentions here the best way for Christians to live. His words indicate that there are degrees of harmony possible among believers. For example, we could imagine that the strong and the weak should form different churches, and if they did that, they would have two churches marked by internal harmony, even although they would not be in harmony with one another.
It is possible that Paul here is drawing the attention of his readers to the Trinity. He mentions a divine person at the start of verse 5, he mentions the second Person of the Trinity at the end of verse 5, and he mentions the first Person in verse 6. So it looks as if the One mentioned at the start of verse 5 is the Holy Spirit, and he is the One who encourages his people and enables them to persevere.
Paul’s words here are in the form of a benediction, which could also indicate that he has the Trinity in mind. It could be that Paul is reminding his readers, as they exist in situations of potential disagreement, to focus on the unity and harmony of the Trinity. They do everything together, and Paul calls his readers to praise the Father together. The implication is that a failure to deal correctly with one another means we cannot praise God in harmony, and he only wants harmonious praise from his people.
Paul gives us insight into intelligent worship. Usually, we worship the Father, and we worship him in a particular way, which is his connection to the Lord Jesus Christ. This is how God the Father wants us to think about him. I suppose we could say that the description of Jesus here is a brief summary of what the Father did for him. The Father gave him the name Lord when he ascended to heaven; the Father gave him the name Jesus when he came into our world by becoming a man; and the Father anointed him with the Holy Spirit in order to fulfil his messianic roles.
Worship of the Father is also a reminder of the doctrine of adoption, that both weak and strong believers belong to his family. Quite often in an earthly family, the children are at different stages of growth, and the younger ones who are weak may act foolishly. But if one of the mature children suggested to their father that they should remove the younger ones from the family he would be appalled. It does not please the Heavenly Father when the price of our worship is to exclude unnecessarily some of his children.
So in verse 7, Paul tells his readers, whether strong or weak, to welcome one another in the same manner as Jesus has welcomed us. He welcomed us with our defects, our misunderstandings, our little grasp of his truth. He welcomed us with the intention of changing us into his likeness in a gentle way. How good it would be if every church practised what Paul describes here, because they would be living for the glory of God and not for their own opinions!