Saint Paul was teaching the gospel he received, along with the theology. The epistles we have are divinely inspired. So it is Christ’s message in that sense. However, we don’t believe Jesus Christ dictated the epistles to St. Paul, or that the epistles don’t include St. Paul’s own thoughts and concerns, even if he was moved to write by the Holy Spirit. Nor is everything he wrote universal theology, in a sense. A lot of the context of what he wrote was to address the specific concerns of the churches he was writing to, in the context of the culture he lived in. That’s not to say it’s not applicable to us or to today, but we must take into accout context. And of course, some things he wrote were definitely meant more universally and generally.