We believe that it is true that if people really understood who God was, His perfection and beauty, His deep and abiding love for them, His goodness and good-will toward His Creation, their need for redemption and His ability to do just that for them, people would be standing line to know Him personally. And perhaps we should begin all of our conversations with the attitude that if they really knew who we were talking about and what He offers them, they would be eager to, at least, enter into the conversation.
But there are also some non-rational (and rational) barriers to that sort of openness.
Some send those signals of reluctance and resistance very clearly through their words 
and by their body language. Other send those signals much more subtly, but again through their words and body language and it’s hard to read...but if you miss reading it or do not handle it well, then all can be lost for that conversation.
And if we’re not obsessive compulsive about getting through some sort of presentation of the gospel and care about the individual as a person as made in the image of God, we can take both our time to listen and time to read their body language. Doing so with skill is one of the great compliments we can pay to those with whom we converse. It’s honest and open and non-manipulative at its best.
That is, virtually all of communication is persuasive in some manner and wanting to persuade others isn’t in itself unethical. Those who disagree can do so, but they cannot legitimately attempt to persuade anyone else of their conviction about that! What we want to do is persuade people who are willing to dialogue about the great things of the gospel and do it in such a way that it is both: 1) non-manipulative and 2) respects both the rational and non-rational nature each of us have.
So how do we read and handle reluctance and resistance?
Well, first resistance to the conversation might not be there, but if it is there we will likely “read” in their choice of words, their dismissiveness and how they say it (their tone) and their facial and body expressions. We’re interested in handling the non-rational component of that resistance here.
So how do you do that? Sometimes it’s helpful to ask them to tell you their experience or their story and when diplomatically appropriate ask them what their spiritual heritage or religious background....and their reaction to it. That’s because sometimes the reason some people resist discussing spiritual things is some extraordinary experience in their family or during their childhood. For instance, if one of their parents was particularly religious and at the same time emotionally disturbed, what would you expect that child to feel about religion generally? Frankly, the whole subject may bring back unwelcome feelings of fear or instability associated with religion. For some who have been molested as a child this can be a very difficult thing to talk about. (Let us say parenthetically unless you are professionally skilled at handling those kinds of issues, you should refer them to qualified people who can help them deal with that.)
Helping people in a very tactful way and pastoral way to realize that these sort of things may be motivating their avoidance may eventually open conversations to greater freedom. And once you hear some of their stories you will no doubt feel a great deal of sympathy for the way the currently feel. But hopefully those experiences won’t play a definitive or final part of their rational appraisal of Christianity.