"He hath endowed every soul with the capacity to recognize the signs of God."

"Say: The first and foremost testimony establishing His truth is His own Self. Next to this testimony is His Revelation. For whoso faileth to recognize either the one or the other He hath established the words He hath revealed as proof of His reality and truth. This is, verily, an evidence of His tender mercy unto men. He hath endowed every soul with the capacity to recognize the signs of God. How could He, otherwise, have fulfilled His testimony unto men, if ye be of them that ponder His Cause in their hearts. He will never deal unjustly with anyone, neither will He task a soul beyond its power. He, verily, is the Compassionate, the All-Merciful."

(Gleanings from the Writings of Bahá’u’lláh, LII, part 2)
www.bahai.org/r/043258227