Everbody takes birth as Sudra

Janmana jayate Sudra, sanskarat Dwija uchyate

Meaning: Everybody takes birth as Sudra , but by virtue of teachings and reforms, can become Brahmin. That means, the son of Brahmin may not be Brahmin or the son of Khatriya may not be Khatriya etc. The caste system based on Gita does not give approval of hereditary or traditional norms of caste classification. Sudra can be elevated to Vaisya, Vaisya can be elevated to Khatriya and Khatriya can be elevated to Brahmin and they are interchangeable.

For example, Rishi Viswamitra was born in a family of Khatriya but he could become a good Brahmin, whereas though born of Brahmin parents, Dronacharya took the profession of a Khatriya .

Similarly, Satyakam was born as a Sudra but he could prove himself to be a perfect Brahmin.

Swami Vivekananda advocated that everybody should try to become perfect Brahmin not by religion but by virtue. There is similar mention in the Buddhist scripture, Dhammapada. According to Gita (14/18) persons with Satta Guna abodes to the upper berth above the heaven, Rajas rest at heaven or below to it, and Tamas at hell or below it. Division of caste on the basis of Triguna or Tri-virtues is very progressive system to build a true secular society. Not only Hindus, but Christians, Muslims, Sikhs-all can be classified as Brahmin, Khatriya, Vaisya and Sudra.