We were discussing this at my church and had some varied opinions. One half says it perfectly normal and natural, another says it's sinful. I really think this needs to be addressed, because if it is sinful, then a lot of people (including me) would be in trouble. What's your opinion on this?
My personal opinion is that it is not sinful. God created men and women for each other. We are sexually attracted to the opposite sex by design, and flirting is part of the mating ritual. We don't live in a society in which marriages are arranged, and expressing our attraction to another is not inherently sinful.
Let's remember that there's a third category of moral situations, not only moral clean, and morally sinful, but also "near to sin" without being sinful. The third category exists for precisely these kinds of situations where there is no clear violation of moral law, and yet it becomes much easier for us to sin. Vice President Mike Pence presents a clear example of this kind of moral prudence. He has a rule of not being with women without a third party being present. You might think that's extreme, but in this era of Harvey Weinsteins, widespread pornography, and normalized moral degeneracy, our Vice President has a clear moral code and a clear conscience.
Flirting becomes a problem when used in an exploitative nature. To either exploit the other, or self, for selfish reasons. It becomes exploitative as soon as one is being deceptive, no matter how subtle. Deception is a lie and a sin. The other problem is that humans are ease victims to self-denial. If truth is seen as getting in the way of attraction then one prone to self-denial and fall into sin.
Btw then Vice President only says he does that because he is married. Flirting while single is obviously not a problem.