Abdul Baha claims that this principle is new:
Furthermore, He proclaims that religion must be in harmony with science and reason. If it does not conform to science and reconcile with reason, it is superstition. Down to the present day it has been customary for man to accept a religious teaching, even though it was not in accord with human reason and judgment. The harmony of religious belief with reason is a new vista which Baha’u’llah has opened for the soul of man.
Abdul Baha, The Promulgation of Universal Peace, p. 455

As usual he contradicts himself elsewhere:
`Ali, the son-in-law of Mu?ammad, said: "That which is in conformity with science is also in conformity with religion." Whatever the intelligence of man cannot understand, religion ought not to accept. Religion and science walk hand in hand, and any religion contrary to science is not the truth.
Abdul Baha, Paris Talks, p. 131.

Abdul Baha confesses that this principle had previously come in Islam - nearly 1400 years ago - in the words of the first Shia Imam, Ali the son-in-law of Mu?ammad. Thus, the claim that this principle is new and novel is unwarranted and baseless.

Regardless of Abdul Baha’s confession about this principle not being new, we will refer to a few Shia narrations about the relation between religion, science, and reason. Imam Ali states:

The Prophets have come to reveal what has been concealed [by God] in the intellects/reasons of the people.
Sayyid Razi, Nahj al-balagha, sermon 1

There are three things that if present in a person, will make their faith complete: reason, patience, and knowledge.
`Abd al-Wahid `Amidi, Ghurar al-Hikam wa durar al-kalim (Qum: Intisharat Daftar Tablighat, 1366 AH [solar]), p. 88, no. 1470

According to Imam `Ali, the prophets were given the duty to plow the people’s reasons and awaken their intellects. Is the meaning of these narrations, anything other than the close relationship between religion, science, and reason? The seventh Shia Imam, Musa ibn Ja`far, states:
God has two proofs upon the people: the outer proof and the inner proof. The outer and apparent are his Messengers, Prophets, and the Imams, and the inner (intrinsic) proof is reason.
Al Kulayni, al-Kafi (Tehran: Dar al-Kutub al-Islamiyya, 1365 AH [solar]), vol. 1, p. 16

This narration also refers to the relationship between religion and reason. Additionally, the accordance of religion and reason was so important in Shia Islam that from the early years of Islam until now, this famous phrase has - and is still - preached by Shia Muslim scholars:
Whatever reason decrees, is also decreed by religion, and whatever religion decrees, is also decreed by reason.

• Religion Must be in Conformity with Science and Reason: Introduction
• Is This a New Principle?
• Did the Founders of Bahaism Follow This Principle?
• Bab’s Religious Orders That Contradict Reason and Common sense
• Bahaullah's Statements That Contradict Reason and Common sense
• Abdul Baha's Statements That Contradict Reason and Common sense - Part I
• Abdul Baha's Statements That Contradict Reason and Common sense - Part II
• Shoghi's Statements That Contradict Reason and Common sense - Part II
• Source of Bahaullah's Education
• Source of Abdul Baha's Knowledge
• Please practice what you preach!
• Is This Principle Correct From a Rational and Logical Perspective?
• Multiple Contradictions by Bahai Founders
• Summary and Conclusion

The articles have been based on the book "Avaze Dohol" - the Beating of the Drum by Masoud Basiti, Zahra Moradi.