A teacher must make the connections between the theological and the practical. He is not to assume that if he throws out a bunch of interesting doctrinal assertions, people will figure out how to apply them themselves. And as noted above, the practical outworking of theological convictions takes place in the church, family and workplace as we interact with people. A belief that doctrine causes division Paul does not shy away from issues that might be considered divisive. The doctrine of the Trinity is assumed in this writing.
Predestination is elaborated on.
The relationship between Jews and Gentiles is addressed. These topics and others are often avoided by teachers afraid of causing division. Such teachers simply mask divisions that exist. Paul expects believers to be unified in the faith, and includes even debated issues that are essential aspects of the faith. The unity of the church is one of the most prevalent subjects in the book.