The first time the virtues were actually defined was done so by Plato and Aristotle. At this time, there were only four virtues: wisdom, justice, temperance, courage. The seven virtues, created to parallel the seven deadly sins, were first found in the epic poem "Psychomachia," or "Contest of the Soul" (by Aurelius Clemens Prudentius in 410 AD). Within the lines of this poem, the seven virtues (in Latin and English) are named: Castatis (Chastity), Temperantia (Temperance), Caritas (Charity), Industria (Diligence), Patientia (Patience), Humanitas (Kindness), and Humilitus (Humility).
In regards to the appearance of these Christian virtues in Beowulf, many of the virtues exist as a characteristic of the epic hero.
Chastity--Although nothing is specifically said about Beowulf being chaste, readers know that he had no children. Therefore, one could assume that the lack of any talk about relationships spoke to Beowulf's chastity.
Temperance- Temperance has been defined as- "proper moderation between self-interest, versus public-interest, and against the rights and needs of others." In regards to this, Beowulf demonstrated temperance when he choose to go and help Hrothgar fight Grendel. Although the battle would bolster Beowulf's already renowned heroic status, he was also able to aid what was best for the public interest.
Charity- Beowulf showed his charity through his desire to help Hrothgar fight Grendel. Not only that, he choose to stay and fight Grendel's mother as well. Although paid handsomely for his deeds, Beowulf did not demand or expect any payment for ridding Heorot of evil.
Diligence- Beowulf was careful and zealous in his actions. He knew exactly what he needed to do in every battle...win.
Patience- Beowulf showed his patience through his battle with Grendel. Beowulf could have attacked the beast as soon as he entered Heorot. Instead, he waited for the exact moment to insure a surprise attack. Although a warrior did die, Beowulf was successful given his patience.
Kindness- Beowulf shows his kindness in a couple different ways. First, he cared about the triumph of good over evil. Therefore, he knew that his presence was necessary at Heorot. It was not only out of his desire to support his renowned name, Beowulf also went to Heorot out of human kindness. Second, Beowulf was always concerned about his people and kingdom. He told Hrothgar that if he died he wanted his riches sent back to his home.
Humility- While a successful warrior, Beowulf always gave the glory of his battles to God. In this sense, Beowulf proved is humility.
Links to the translated and original text of "Psychomachia" are linked below.