Look into everything with a searching eye

Bahá'u'lláh said:

Look into everything with a searching eye.

Each individual human being should investigate spiritual truth for himself. His relationship to Almighty God is the responsibility of no one but himself. He can, and should, learn from the knowledge and experience of others, but he should not
accept their findings as the final truth for himself without a careful personal investigation.

That this search for spiritual truth would require constant effort we are told in the Bible. Deuteronomy says:

If from thence thou shalt seek the Lord thy God, thou shalt find him, if thou seek him with all they heart and with all thy soul.
Deuteronomy 4:29

William Sears, Thief in the Night, p. 228

If, in the Day when all the peoples of the earth will be gathered together, any man should, whilst standing in the presence of God, be asked: "Wherefore hast thou disbelieved in My Beauty and turned away from My Self," and if such a man should reply and say: "Inasmuch as all men have erred, and none hath been found willing to turn his face to the Truth, I, too, following their example, have grievously failed to recognize the Beauty of the Eternal," such a plea will, assuredly, be rejected. For the faith of no man can be conditioned by any one except himself.

Bahá'u'lláh, Gleanings from the Writings of Bahá'u'lláh, p. 143