Terry, correct me if I'm wrong, but you know that even if the greatest and most logical minds were to devote themselves to the understanding of something complex, that (even though there is in fact one truth) there would very likely still be disagreements among them, no? If this is the case then you are actually saying--not that we must all arrive at the same understanding--but that we should at least do our very best to make sure our beliefs and ideas are our own, and not the deposits of some cuckoo.
Man has figured out how to feed billions.
Man has discovered how the heaven's move to such a degree of accuracy he can aim a heavy metal vehicle at a tiny stone swirling in the vast universe, lift it in defiance of gravity and land there and return.
Man has powered teaming cities that lay in darkness with electric lights. Man has cooled buildings so tall the ancients would faint at their exquisite proportions.
The mind of man has penetrated the beautiful secrets of existence in mapping the human genome. He has harnessed the power of the tiniest component of nature: the atom. He has extended the life span from 30 or 40 years to double or more. He has created replacement parts for the heart and limbs.
The intellect of man has given us travel at supersonic speeds; flights to the moon, glimpses of the farthest reaches of the universe and scrutiny at the most vanishingly small components of nature itself.
Man is self-improving, self-programming and unlimited. He can only be thwarted by abandoning his supreme advantage over all other life forms: REASON itself. When man doubts his own worth, as religion teaches him he must, he withers and cowers under the shadow of fear projected from malevolent minds who seek to use him as a leech uses the wayward flesh of unwitting prey. The mystics rob man of his labor and create an idle nothing in its place.
When reason is abandoned; when the rational mind is doubted as a power to inform, the light goes out in the citidel of man's integrity and he becomes the most useless of all creatures as he serves the whims of others. In the role of slave and servant, man is but a fool's fool. He is a trinket, a bauble around the neck of latter day Atillas and Hitlers to use as they will.
To answer your question specifically:
Men need not have identical understandings to be men. No. To be men they must mightily strive to reach for the heavens with a sharpness of eye and quickness of thought to appraise the means by which miracles can be wrought by dint of sheer keeness of observation, calculations and cunning.
The greatest immorality is the abandonment of reason. The open door to evil is when men shrink from absolute adherence to what reality informs them must be true. Man must never waver in his thirst, his passion for a path to self-perfection. A goal he knows he'll never achieve; but, the magnificence of the prize empowers his quest none-the-less.
Doubt everything until it is proved to your satisfaction. Let your standard be the highest imaginable. Be ruthless in uprooting dissonant and tainted ideas which serve you ill. Always be willing to be wrong while endeavoring to be as right as a 90' angle. Demand excellence and tolerate no compromise with error. Make fierce war upon fallacy, superstition and second-hand hearsay. Allow no breach in your excellence and you'll be well on your way toward plucking the stars of heaven from their perch to illumine your mind with the bright and earnest brilliance of superlative skill in thinking golden thoughts studded with transcendant IDEAS.
Terry
p.s. I hope this answers your query