I am a Brahmin by birth

The word Brahmana (hereinafter "Brahmin") means the God, one who knows God, one who has the knowledge of God, one who has the knowledge of Vedas, an intellectual, a priest, a teacher, a professor, a person belonging to Brahmin caste, a superior person, a text related to Vedas, and so on. Accordingly, priests in a mosque, church, a synagogue, a gurudwara etc. are all Brahmins because they are all , obviously, priests. They are also Brahmins because they are supposed to have the knowledge of God. They are also Brahmins because they are intellectuals.

The Brahmins conducted the daily rites, the purification ceremonies, sacrifices and taught the Vedas. Since they were the teachers, preachers and priests they had to be proficient in sacred knowledge through the Vedas. They were to be kind and gentle. For this, they earned certain privileges. They were regarded as the highest class and respected by all, to the extent that they were treated almost like gods by commoners and kings alike.

The belief that people born in Brahmin caste, automatically become Brahmins, is a much later concept in the very ancient land of India. In the pre-Gita period (before the beginning of the Christian era) a Brahmin was a person who had attained highest spiritual knowledge (brahmavidya). This was an extremely difficult path of discipline of body, mind , and intellect, and people irrespective of their birth or class, who dedicated to such an austere life were recognized as Brahmin's.

Initially, a person became a Brahmin on the basis of his knowledge of the Vedas.

A smritis, or code of conduct composed by sage Atri defines brahminhood very clearly.

"By birth, every man is a Shudra (an ignorant person). Through various types of disciplines (samskaras), he becomes a dwija (twice born). Through the studies of scriptures, he becomes a vipra (or a scholar). Through realization of supreme spirit (brahmajnana), he becomes a brahmin"

Note: Hindus consider people in the the top three classes — Brahmins, Kshatriyas, and Vaisyas — "twice born." This has nothing to do with reincarnation; according to Hinduism, everyone gets reincarnated. A person who is "twice born" is born once as a baby and then goes through a ritual to become an adult.