a. "unresolved sin" on the part of the preacher of the word? Or it is "your fault" for not preaching a perfect sermon and not being "good enough" to personally influence the hearers?
b. Man's depravity making man an enemy of God unless and until the Lord steps in and changes the heart of man?
My preference is for B for this reason: Christ Himself preached and had people turn from Him in droves when He was on the earth.
Merry Christmas Dan!
Second, it certainly is a fear to me personally that something in my preaching or witnessing would obscure Christ and His gospel. And more in the abstract, it is certainly possible to preach another Jesus and a false Gospel, to the damnation of both preacher and hearers (2 Corinthians 11:4; Galatians 1:6-9).
But it is certainly possible to preach the Gospel accurately, truthfully, and in the power of the Holy Spirit, and still have some or all hearers respond with hatred and rejection, or indifferent shrugs (cf. Acts 7:54ff.; 17:32). And in those cases, the cause is entirely in the hard, God-hating hearts of the hearers.
Does that answer your question?
Dan