In late August of 386, at the age of 31, having heard of Ponticianus's and his friends' first reading of the life of Anthony of the Desert, Augustine converted to Catholicism.
As Augustine later told it, his conversion was prompted by hearing a child's voice say "take up and read" (Latin: tolle, lege).
Resorting to the Sortes Sanctorum, he opened a book of St. Paul's writings (codex apostoli, 8.12.29) at random and read Romans 13: 13–14: Not in rioting and drunkenness, not in chambering and wantonness, not in strife and envying, but put on the Lord Jesus Christ, and make no provision for the flesh to fulfill the lusts thereof.

He later wrote an account of his conversion in his Confessions (Latin: Confessiones), which has since become a classic of Catholic theology and a key text in the history of autobiography.
This work is an outpouring of thanksgiving and penitence.
Although it is written as an account of his life, the Confessions also talks about the nature of time, causality, free will, and other important philosophical topics.
The following is taken from that work:
Belatedly I loved thee, O Beauty so ancient and so new, belatedly I loved thee.
For see, thou wast within and I was without, and I sought thee out there.
Unlovely, I rushed heedlessly among the lovely things thou hast made.
Thou wast with me, but I was not with thee.
These things kept me far from thee; even though they were not at all unless they were in thee.
Thou didst call and cry aloud, and didst force open my deafness.
Thou didst gleam and shine, and didst chase away my blindness.
Thou didst breathe fragrant odors and I drew in my breath; and now I pant for thee.
I tasted, and now I hunger and thirst.
Thou didst touch me, and I burned for thy peace.

Ambrose baptized Augustine and his son Adeodatus, in Milan on Easter Vigil, 24–25 April 387.
A year later, in 388, Augustine completed his apology On the Holiness of the Catholic Church.
That year, also, Adeodatus and Augustine returned home to Africa.
Augustine's mother Monica died at Ostia, Italy, as they prepared to embark for Africa.
Upon their arrival, they began a life of aristocratic leisure at Augustine's family's property.
Soon after, Adeodatus, too, died.
Augustine then sold his patrimony and gave the money to the poor.
He only kept the family house, which he converted into a monastic foundation for himself and a group of friends.

In 391 Augustine was ordained a priest in Hippo Regius (now Annaba), in Algeria.
He became a famous preacher (more than 350 preserved sermons are believed to be authentic), and was noted for combating the Manichaean religion, to which he had formerly adhered.

In 395, he was made coadjutor Bishop of Hippo and became full Bishop shortly thereafter, hence the name "Augustine of Hippo"; and he gave his property to the church of Thagaste.
He remained in that position until his death in 430.
He wrote his autobiographical Confessions in 397–398.
His work The City of God was written to console his fellow Christians shortly after the Visigoths had sacked Rome in 410.
Augustine worked tirelessly to convince the people of Hippo to convert to Christianity.
Though he had left his monastery, he continued to lead a monastic life in the episcopal residence.

Much of Augustine's later life was recorded by his friend Possidius, bishop of Calama (present-day Guelma, Algeria), in his Sancti Augustini Vita.
Possidius admired Augustine as a man of powerful intellect and a stirring orator who took every opportunity to defend Christianity against its detractors.
Possidius also described Augustine's personal traits in detail, drawing a portrait of a man who ate sparingly, worked tirelessly, despised gossip, shunned the temptations of the flesh, and exercised prudence in the financial stewardship of his see.
In late August of 386, at the age of 31, having heard of Ponticianus's and his friends' first reading of the life of Anthony of the Desert, Augustine converted to Catholicism. As Augustine later told it, his conversion was prompted by hearing a child's voice say "take up and read" (Latin: tolle, lege). Resorting to the Sortes Sanctorum, he opened a book of St. Paul's writings (codex apostoli, 8.12.29) at random and read Romans 13: 13–14: Not in rioting and drunkenness, not in chambering and wantonness, not in strife and envying, but put on the Lord Jesus Christ, and make no provision for the flesh to fulfill the lusts thereof.
He later wrote an account of his conversion in his Confessions (Latin: Confessiones), which has since become a classic of Catholic theology and a key text in the history of autobiography. This work is an outpouring of thanksgiving and penitence. Although it is written as an account of his life, the Confessions also talks about the nature of time, causality, free will, and other important philosophical topics. The following is taken from that work:
Belatedly I loved thee, O Beauty so ancient and so new, belatedly I loved thee. For see, thou wast within and I was without, and I sought thee out there. Unlovely, I rushed heedlessly among the lovely things thou hast made. Thou wast with me, but I was not with thee. These things kept me far from thee; even though they were not at all unless they were in thee. Thou didst call and cry aloud, and didst force open my deafness. Thou didst gleam and shine, and didst chase away my blindness. Thou didst breathe fragrant odors and I drew in my breath; and now I pant for thee. I tasted, and now I hunger and thirst. Thou didst touch me, and I burned for thy peace.
Ambrose baptized Augustine and his son Adeodatus, in Milan on Easter Vigil, 24–25 April 387. A year later, in 388, Augustine completed his apology On the Holiness of the Catholic Church. That year, also, Adeodatus and Augustine returned home to Africa. Augustine's mother Monica died at Ostia, Italy, as they prepared to embark for Africa. Upon their arrival, they began a life of aristocratic leisure at Augustine's family's property. Soon after, Adeodatus, too, died. Augustine then sold his patrimony and gave the money to the poor. He only kept the family house, which he converted into a monastic foundation for himself and a group of friends.
In 391 Augustine was ordained a priest in Hippo Regius (now Annaba), in Algeria. He became a famous preacher (more than 350 preserved sermons are believed to be authentic), and was noted for combating the Manichaean religion, to which he had formerly adhered.
In 395, he was made coadjutor Bishop of Hippo and became full Bishop shortly thereafter, hence the name "Augustine of Hippo"; and he gave his property to the church of Thagaste. He remained in that position until his death in 430. He wrote his autobiographical Confessions in 397–398. His work The City of God was written to console his fellow Christians shortly after the Visigoths had sacked Rome in 410. Augustine worked tirelessly to convince the people of Hippo to convert to Christianity. Though he had left his monastery, he continued to lead a monastic life in the episcopal residence. 
Much of Augustine's later life was recorded by his friend Possidius, bishop of Calama (present-day Guelma, Algeria), in his Sancti Augustini Vita. Possidius admired Augustine as a man of powerful intellect and a stirring orator who took every opportunity to defend Christianity against its detractors. Possidius also described Augustine's personal traits in detail, drawing a portrait of a man who ate sparingly, worked tirelessly, despised gossip, shunned the temptations of the flesh, and exercised prudence in the financial stewardship of his see.
Augustine of Hippo