Honesty? Impossible - But Negotiable, Of Course
It seems obvious that nobody can ever be honest at all times. Nor can we be absolutely against stealing and killing. These are negotiable, as are many issues in life. Usually we are for honesty and against killing and stealing, but killing can earn us the highest medal for valour, and the morality of stealing certainly depends on the circumstances, while complete honesty as to a loved one's whereabouts may doom that person to death.
No hunter is ever entirely honest with his prey. No soldier will reveal everything to the enemy who is trying to kill him. No starving colonized native is going to be completely forthright with the European plantation owner who forces him from his ancestral lands. In fact, it is ridiculous to consider the question of honesty except in relation to the more fine-grained question: Honest with whom? This brings us immediately to matters of loyalty, and thus to herds and the herd instinct. We risk getting into the biology of competing organisms, and even of our own tissues, which can reject very slightly different ones, or mistakenly identify self as foreign.
Many religious positions deal with absolutes. Often these are based on unexamined premises, which, for Heaven's sake (pun intended), must be the soul of dishonesty. All too often such stances remind us of Alice and Humpty, and his dictum that what really matters is who is to be master. So once again the question of honesty gives way to defining the terms we use, and to defining our interests in a situation. Perhaps clarity can be brought to the whole issue of honesty by one attempt to define its opposite: "A lie is an untruth told to someone who deserves to hear the truth".