The word "repent" appears in the New Testament and in Christian literature and sermons. And yet it seems to be the result of a faulty translation, a translation faulty enough to distort our view of both Jesus and God.
The word "repent" is derived from the Latin paenitere, which means to regret or be sorry, from which we also derive the words "penitent" and "penitentiary." But the Greek word used in the manuscripts of the New Testament is metanoia, which means to change your mind or change your heart. (See "The Lost Gospel Q," Marcus Borg, ed., p. 34, n. 1.)
John the Baptist was not calling on people to express regret or feel guilty, but to renew their minds and hearts. Mark 1:4 (NRSV) says that John was proclaiming "a baptism of repentance for the forgiveness of sins." In "The Lost Gospel Q," the same phrase is translated as "baptism and a change of heart leading to the forgiveness of sins." In "The Gospel According to Jesus," Stephen Mitchell translates the phrase as "a baptism of renewal for the forgiveness of sins."
The act of forgiveness is itself a change of heart or change of mind. When we forgive, we go from anger, resentment, or disapproval to a state of peace, love, and non-judgment. Similarly, we are "reborn" in Jesus because we can then change our hearts, putting aside our fears and sorrows and regaining the faith and innocence of a child.
It is true that, in the parable of the prodigal son (Luke 15:11-32), the son who has lead a sinful and dissolute life admits to his father that he has sinned when he returns home, but the father does not seem to pay any attention at all and immediately calls for a celebration. The son is never asked to perform any penance and his sincerity is never questioned. The son never even asks for forgiveness. He is simply accepted home and unconditionally forgiven as soon as he appears. His change of mind and decision to return home was enough.
Renewal and rebirth are central to the teachings of Jesus, and it is unfortunate that we have become burdened by the idea that we have to be penitent before we can be reborn and return to God.