In a city there are kindergarten schools, elementary schools, high schools, colleges and maybe a university. From the kindergarten and up to the university, all the institutions are called the educational institutions and their aim is to remove illiteracy and make a person educated, but all of them are not for all the people of that town. They have classifications according to merit as to who could be admitted to which institution and in which grade or in which kind of study.
Similarly, all of our scriptures are collectively called “Sanatan Dharm” which means the eternal (sanatan) knowledge for the spiritual well being of all the souls (dharm). It provides the guidelines for all kinds of people of the world, which, if followed, leads them towards God realization. But the scriptures of Sanatan Dharm, like the various educational institutions of a town, are specified according to a person’s receptivity for God as to which scripture one should follow.
The Vedas: For example: A wicked person should at least think of God that He knows everything, so He will punish him for his wicked deeds. A selfish and worldly person should at least follow the disciplines of the Vedas and do good deeds and learn to pray to any form of God or he may do any ritualistic yagya* even with a worldly desire to obtain the celestial luxury.
*The technical requirements of doing a yagya are hard to fulfill in kaliyug. Thus, the Sages have promulgated that the Vedic yagyas are not suitable for kaliyug, and so, only the good deeds, prayer and honest behavior as mentioned above should be observed by those kind of people in this age.
The other good actions which are also involved in the performance of the yagyas are: giving charity, maintaining piousness and celibacy during the period of doing yagya, and praying to God for the purification of the mind; and afterwards he is supposed to observe honest behavior in his life. These good actions slowly purify the heart of the doer, and thus, he could become qualified to enter into direct devotion to one form of God which is like taking an admission into high school from an elementary school.
The Upnishads: When a person begins to feel a real liking for God but still he is attached to his material enjoyments and he keeps on doing good deeds, the Upnishads help him at this stage and tell him about the futility of worldly pleasures and advise him to renounce worldly attachments and wholeheartedly love God.
The Gita: When the person enters into such a stage of heart purification where he really begins to realize the worthlessness of worldly pleasures and feels an urge to meet God, the Gita tells the secret of devotion, and says that devotion to God is selfless bhakti, which means selflessly loving Him and living in the world to fulfill your aim of the realization of His Divine love. Selflessness means not desiring any worldly thing from God but desiring only for His love and His vision.
The Bhagwatam: When a devotee has understood the importance of pure and selfless bhakti,then the Bhagwatam tells the devotee that the sweetest and the real intimate form of God is Krishn Whose bewitching beauty had enchanted everyone who was living in Braj at that time.
When a devotee is fallen in love with Krishn then the writings of the rasik Saints tell about the richness of the Blissful stages of Divine love which are experienced in Golok and in Divine Vrindaban.
Thus, the Vedas tell to become a good person; Upnishads tell to love God and don’t be attached in the world because it is illusion; the Gita tells to love God selflessly and reveals the secret of the spiritual practices that only through bhakti one can realize God; and then the Bhagwatam tells what is the most loving form of God that encharmed the heart of the topmost Yogi and Gyani, Shukde
Now we know that our scriptures are a very systematic line of teachings. They relate to every class of people of the world from an ordinary worldly person to a highly evolved soul deeply longing to meet God. But, every scripture is not for everyone; just like a book, prescribed for postgraduate classes, is no good for the student of a lower grade; and vice versa. However, as a whole, all the scriptures represent such Divine teachings which accommodate the spiritual need of all the souls of the world and show the path of God realization. This is Sanatan Dharm or the Hindu religion which is the “universal religion” for the whole world that originated directly from the supreme God.It was first introduced by Brahma to the Sages and Saints of this brahmand who produced it for the people of the earth planet. Lastly it was again reproduced by Bhagwan Ved Vyas about 5,000 years ago and its Divineness was further magnified in the celebrated writings of our great acharyas.