People in need of proofs as Manifestation has gone

Since the Manifestation has gone, all stand in need of proofs

"Now, since that Luminary of truth has set, all stand in need of proofs, and so we have been occupied with providing rational proofs."

('Abdu'l-Bahá, Some Answered Questions, Chapter 10, par. 2)

The "Veils" are Very Thin at the Time of the Manifestation

"As to the words of ‘Abdu’l-Bahá about the 'vineyard will not then be so easy to find', etc. This supports many such remarks: He explained often that at the time of the Manifestation the veils are very thin, so to speak. Many souls accepted seemingly spontaneously, on the basis of a dream, or just hearing the Cause existed! But later, this first phase passes, and the people require more arguments and proof, acceptance comes less as a flash of spiritual insight and more as an intellectual process. This is quite different from the future glory of the Cause and the divine origin of its institutions, graphically outlined by Him."

(From a letter written on behalf of Shoghi Effendi to an individual believer, November 25, 1947, in Lights of Guidance, no. 1587)