Tamāla Kṛṣṇa: "In this verse the Lord explains the same more clearly. Sāṅkhya-yoga, or the analytical study of the nature of spirit and matter, is the subject for persons who are inclined to speculate and understand things by experimental knowledge and philosophy. The other class of men work in Kṛṣṇa consciousness, as is explained in verse sixty-one of the same Second Chapter. The Lord has explained also in verse thirty-nine that by working under the principles of buddhi-yoga, or Kṛṣṇa consciousness, one can be relieved from the bonds of action, and furthermore there is no flaw in the process.
"The same principle is more clearly explained in verse sixty-one, that this buddhi-yoga is to depend entirely on the Supreme, or more specifically, on Kṛṣṇa, and in this way all the senses can be brought under control very easily. Therefore both the yogas are interdependent, as religion and philosophy. Religion without philosophy is sentiment, or sometimes fanaticism, while philosophy without religion is mental speculation. The ultimate goal is Kṛṣṇa."
Prabhupāda: There are certain class of men who are simply philosophizing, and there are certain class of men who are simply blindly following religious ritualistic processes. So Bhagavad-gītā is combination of both. That is scientific. You should be religious, but should understand everything philosophically, not . . . otherwise one becomes fanatics, religious fanatics. In the Caitanya-caritāmṛta it is clearly said that caitanyera dayāra kathā karaha vicāra (CC Adi 8.15): "You people, you try to understand the gifts of Caitanya Mahāprabhu by your philosophical understanding." Not blindly; philosophically. And vicāra karile citte pāibe camatkāra: "If you are actually a wise man, then you'll find it is sublime." And if you simply stick to your own religious ritualistic principles—don't try to understand the philosophy of everything—then you become a fanatics.
So we should not become religious fanatics, nor dry mental speculators. Both these classes of men are dangerous. They cannot make any advance. The combination. You should be religious, but try to understand each and every line philosophically.
Just like in the Bible there is the statement, "God created this universe." It is a fact. But because modern educated persons have not explained how God created, how the process of creation . . . these things are explained in the Bhāgavata, how the sky became in existence, then the air became in existence, the fire became in existence. There is a process, general graduation. Actually, God has created the world. There is no doubt about it. But because it is not philosophically explained, the modern educated person, they don't accept.
So Bhagavad-gītā you'll find everything: a combination of religious sentiments plus philosophical understanding. That is wanted.