“Tell the maiden whose hair shines in the sun that she is the daughter of the morning.
But if you shall behold the sightless, say not to him that he is one with the night.” ~Kahlil Gibran
It is helpful to to tell those who are seeking enlightenment whatever you can to get them on the right path. It is good to compliment them when they are making progress. Sometimes, it is even good, when you meet someone with potential, but who is still “sleeping” to give them a slap to wake them up.
It is pointless, however, to waste time telling those who are lost to darkness, that they are lost in the dark. First, they won’t believe you because what you can see is darkness, they think is a form of enlightenment. Second, even if you convince them that they are stumbling about in the dark, if they do not have the potential to awaken their soul and become enlightened, then you are not aiding them by informing them that they are one of the lost. Let them live their pointless lives in what limited happiness they can have, and who knows, they may actually accomplish something useful to all despite being spiritually lost. Also, you can open yourself to psychic attacks from those trapped in the dark who become angry when you point out their condition.
Of course, part of the problem is knowing who falls into which group. We all like to think that all of our friends and relatives have the potential to become enlightened, but that is an unrealistic expectation. So if we know that a person, no matter how much we love them, is not, and never will be, interested in spiritual development, we should not bother trying, but, if we think there is some possibility that they will awaken, or can be awakened, then we should try. But we have to learn to not be too disappointed when we fail, because there are those who simply cannot be awakened, and those who may be ready at some time in the future, but not now. On the other hand, there may be people we really don’t like, but we recognize that they are seeking truth and need a little guidance. We should give that guidance as part of our duty, even if we don’t care for the person.