Sometimes preachers preach doctrine where the Bible preaches duty.
They replace the doxology of Christian living with the theology of Christian history. Both duty and doctrine are vital; they cannot substitute one for the other.
Attempting to substitute doctrine for duty or duty for doctrine is like giving birth to twins and saying, “Only one will do.” No. The mother and father leave the hospital with both children counting themselves doubly blessed.
So it should be with our preaching of both sound doctrine and the solid duty that comes from it.