2 Corinthians 5:12
The Corinthian church had a tendency to elevate ministries that looked and sounded impressive. However, Paul understood that showy itinerants were not necessarily bringing a message that will transform lives.
To tackle this, Paul encourages them to take pride in what's in the heart rather than what's seen. In other words, has the ministry resulted in the improvement/transformation of their character?
Paul emphasises the importance of having a sincere heart, and walking in new covenant will result in sincerity; an earnestness to be in friendship with God.
Walking in old covenant can promote insincerity because it's driving force is the maintenance of a list; do this, don't do that, not like that, do it like this etc. We can have an outward appearance of doing all the right things, but has our heart changed to match?
Walking in New covenant takes pride in the change of heart, more than the outward appearance of a spectacular ministry or spirituality.
The sincere heart that Paul describes is connected to the sacrifices he'd made as listed in 2 Corinthians 6:4-6. Only a person who is utterly sincere and devoted to their message, would go through violence, hardships and 'calamities of every kind'.
The 'super apostles' on the other hand, were rich in dress and speech, but preaching a gospel that didn't change the human heart.
Reading 2 Cor 1:14 it seems the Corinthians didn't understand Paul well enough to take pride in him and celebrate his ministry. They tended to favour flashy guest speakers over Paul who came back from ministry tours bedraggled, beaten and sleep deprived. It's ok to look good and sound confident, but if the message is wrong, the church will become spiritually impoverished.
In defense of his ministry AND the true gospel, Paul urges the church to look past the spectacular, past the designer clothes, past the smooth speech and past a 'popular' message - to the transformation of hearts!
The new covenant preached by Paul may not sound or look regal, but it will result in a royal heart.