Yes, the Seventh Ray, The Supreme Sign, points out thirty-three vast, universal, unanimous proofs in all beings. Alluding to innumerable evidences in each universal proof, it proves firstly that heavens indicate the Necessarily Existent One’s existence and unity with the words of the stars; the earth with the phrases and sentences of the animals and plants; and so on, until the universe as a whole, with the words of all its contents and beings, and the truths of contingency and createdness and change — it proves them as clearly as sunlight and as certainly as the day.

Those who want unshakeable belief and seek an unbreakable sword to combat irreligion and anarchy should refer to The Supreme Sign. Bediüzzaman Said Nursî.

If you wish to have unshakeable iman (belief), here is the Supreme Sign.