It’s a difficult question to deal with. A person may be “less than religious” may even be “irreligious”, but everyone, by strict definition is religious.
Most people, when they think of “religion”, they think of it in relationship to a deity of sorts. This is a common misconception, especially among those who would like to disassociate from a past experience that was either bad or unimpressive.
Strictly speaking, a religion is a habit, and habits can be good or bad, helpful or hurtful, useful or useless. Now, how those terms are applied are definitely up for grabs in the world of competing philosophies, but ultimately one, even if they don’t want to admit it, is religious.
“Well”, one may retort, “you know what I mean.” To which I can most certainly reply, “I know what not only the word means, but its implication to the matter.” That may seem like a smart-alecky response, but it is a true response. For someone to declare that they are “not religious” just to get around a question is not only being dishonest with the other party, but self-deceptive on the whole. The best way to phrase such a statement would be to respectfully state, “I just don’t believe that”, or, “I don’t agree with that.” And lucky for you, that opens up an entirely new avenue of conversation, where what you do believe can be called into question, and examined more thoroughly. Who knows, maybe it will take something of no value and make it highly valuable.