I charge you in the presence of God and of Christ Jesus, who is to judge the living and the dead, and by his appearing and his kingdom: preach the word;....(2 Timothy 4:1,2)
Recently I was again exposed to the negative aspects of "topical preaching." So often, I am tempted to say "always" but won't, so often, the preacher takes his heart's Topic and drags in every scripture verse he can find in support of his own view as he builds his "case."
The result is a man-made conglomeration of error and half-truths and the Word of God lies mangled at the preacher's feet. I speak as one who has fallen into this trap more than once. I have hobby-horses just like most men do. I have "proof-texts" too. But that imperative "preach the Word" does not mean: preach what you think is right and torture the scriptures as necessary in order to support your theme.
The art of expository preaching, where one preaches through a text verse-by-verse, protects both the preacher and the hearers from much of the error which can come from the work of sinful men, even regenerated sinners. The Word acts as a restraint upon our passion to promote our own ideas and pet theories. We should be, by this framework, held close to the intent of the Holy Spirit Who penned the words of the text. It is so easy to grab a verse somewhere because it "sounds good" in support of our topic when in fact, it is being used out of context, either grammatical or historical, or both.
"Preach the Word" means preach His Word, not ours.