Now I myself am confident concerning you, my brethren, that you also are full of goodness, filled with all knowledge, able also to admonish one another. (Romans 15:14)
Paul has been addressing a somewhat tense issue among the Christians in Rome since the beginning of Romans 14.
Romans 15:14 shows that Paul was confident these Christians would respond as they should, and handle the situation the correct way. He was confident because of three things about them.
“You are full of goodness.”
Thayer defines the word “goodness” as “uprightness of heart and life.”
The Christians in Rome were good, virtuous, generous people, who were truly concerned about others - not just themselves.
Paul complimented his readers for being outward-looking and not concerned only for themselves. He implied that, regardless of whether members were Jewish Christians or in the Law-free camp, they cared about each other. - Pollard, Truth for Today Commentary, 537
Their being “full of goodness” motivated them to make whatever sacrifices they needed to make for the good of the brethren - for the good of the Lord’s church.
Paul was confident that could handle whatever situation arose because they were “full of goodness.”
“You are filled with all knowledge.”
This probably refers to how the Roman Christians knew everything they needed to know to handle the tense situation about matters of opinion.
[Paul’s] mention of their “knowledge” may have especially concerned their recognition of the rightness of what he had written about Jew/Gentile issues. The last compliment was very relevant to the Roman situation and indicated Paul’s confidence that these Christians could work out the problems that existed in the house churches. - Pollard, Truth for Today Commentary, 537
Paul had confidence that they were able to handle these issues because (1) they were “full of goodness) and (2) because they knew all they needed to know about these things.
When the church’s knowledge and attitude are what they need to be in the Lord, what a beautiful thing that is!
“You are able to admonish one another.”
Having the knowledge they needed of the situation, and also being full of goodness, meant they were able to “admonish” or to “caution" or “warn” (Strong) those who needed a warning.
Those whose knowledge is sufficient, but are lacking in goodness - there’s not a lot of confidence in those folks that they were effectively be able to admonish others.
But also, those who may be full of goodness while lacking in knowledge will also fall short in admonishing others as they should.
Paul’s confidence that they would appropriately handle the situation was based on them being both “full of goodness” and “filled with all knowledge.”
Paul is not flattering these brethren.
He is genuinely praising them based on what he knows to be true about them. How encouraging it is when we know God’s people (1) are who they should be and (2) know what they should know.