What does it means to have a duty to recognize God’s Messenger?
If I told you there were things about astronomy you did not know, it’s pretty easy for an honest person to recognize that indeed, you do not know them. Perhaps it might require a little proof, but ignorance is easily uncovered by the willing seeker.
Let’s say you want to be an astronaut. I claim it’s your duty to familiarize yourself with those details of astronomy, otherwise there’s no chance of your heading into space – or at least, you’d have to be extremely lucky (blessed?) to reach where you wanted to go.
Bahá’u’lláh tells us that God’s creation is ordered according to spiritual laws, and that our own reality, being spiritual in nature, cannot grow or become fulfilled except through acting within the sphere of those laws.
Thus it is the duty of anyone who wishes to become a servant of God, to recognize the fact of his own nature, and that no truth he finds is genuine unless it be encountered within the confines of His Law (of which there are both general and specific aspects).
The analogy does go further, since it’s quite possible for someone to obey a physical law without understanding it. But the perfection of nature cannot be unveiled without close attention to the laws governing it. It’s one thing to discover fire; it’s another to reach out bodily toward the heavens.
So while God’s grace is liberally diffused over all human kind, and no one is threatened by extinction (according to my reading), it is another question entirely who will make the choice to plumb the hidden Depths.
To sum: A student who would attend a school must realize that his teachers are there to teach, and he is there to learn. Thus a recognition of station takes place, followed by an obedience of the laws existing between those two spheres of being. Ignoring that duty leads to expulsion from the school (albeit, not from life, or from trying again). So if we wish to be heedless beings, it is our choice. But there is Door waiting to be opened, a door whose key one must turn with the hand of endeavor, and not just a hopeful wish.