Well, if you follow the pope’s teaching, you are certainly part of the Universal Church established by Christ.
But if you don’t follow the pope’s teaching, then it is hard to know what you are part of. You may actually be following Christ, or you might not be.
The Bible is a book that does not specifically address many things in life - and so an actual authority is needed to teach definitively in accord with the truth found in the Gospel. If there is more than one final earthly authority, unity is impossible. Only those who share the same final earthly authority can have unity.
Well... if the pope's teachings are consistent with Holy Scripture, since we both agree God's word is THE final authority, we follow Christ. This is the universal church established by Christ (no real need for capital letters), a spiritual body where Jesus Christ is the head and Good Shepherd.
As far as what the Bible doesn't "specifically address", I believe they are not the critical doctrines that pertain to what one must know to have eternal life. That is something God most definitely covered the bases on. The other areas are covered just maybe not in quite the same specific way, which does leave liberty in minor issues.
In major things - UNITY
In minor things - LIBERTY
In all things - LOVE