If so, then humans will never understand the message of Bahaollah. Clearly, he failed in his mission. Why did he make it so lengthy? 17,000 'tablets' apart from the books? And on top of it writings by his son, great grandson, your House of Justice and various other Bahai personages!
We are an ever advancing civilization. The dispensation of Baha’u’llah will span 500,000 years. This message is suited for 1000 years, we are just at the beginning. The future Messengers will further expand on the knowledge released by the Bab and Baha'u'llah.
The Bible foretold this in John 16 we read;
 I have yet many things to say unto you, but ye cannot bear them now
.  Howbeit when he, the Spirit of truth, is come, he will guide you into all truth
: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come."
Notice Baha'u'llah will guide us unto all truth and will show us things to come, exactly what happened.
When war ceases, when we find unity, the capacity of humanity will be released from its bandage to this material world and great things will be uncovered. At the moment we have used science mostly for the destruction of each other, a lot of good discoveries were born out of the need to find weapons, rather then to assist humanity to find its God given capacity.
I would rather discuss this, than to approach it from having to defend the legitimacy of the Message of Baha’u’llah.