Acts 28:24 And some believed the things which were spoken, and some believed not.
A basic truth is very well illustrated for us here in this verse. No matter who is preaching some will believe and others will not. That is not the question that we have to answer. The question we answer is will we share enough with them that they can make a decision.
I am afraid that we have allowed fear of failure to cause us not to talk at all. Even when Paul spoke not all would be saved, not all would believe. He still told the truth.
Will you work at sharing the truth with others. Some will believe, others will not. Your responsibility is the telling not the result of the telling.