In Shakespeare's Romeo and Juliet, in Act I, scene v, state the meaning of "gentle sin" as Romeo compares Juliet to a.........

In Act One, scene v, in Shakespeare's Romeo and
Juliet, the two lovers are meeting for the first time at a Capulet party.
Neither of them know that the other is a member of their family's
enemy.

When they meet, Romeo and Juliet flirt first with
words. He compares Juliet to a shrine, and his lips to pilgrims—travelers who visit holy
shrines to give thanks and worship. (These are
metaphors.)

If
I profane with my unworthiest hand / This holy shrine, the gentle sin is this: / My
lips, two blushing pilgrims, ready stand / To smooth that rough touch with a tender
kiss. (I.v.98-101)

Romeo
declares that Juliet is line a shrine—a holy
place.

Dictionary.com defines a shrine
as:

...any
structure or place consecrated or devoted to some saint, holy person, or deity, as an
altar, chapel, church, or
temple.

The extended metaphor
created here between the two as they continue to speak and even kiss, uses references
with a religious motif. Once Romeo identifies the young Juliet as a shrine, he says that
if he has offended her, he will, like "two blushing pilgrims" smooth his offense (his
"gentle sin") with a kiss.

Juliet responds that he is too
harsh regarding the sin of his hands, and continues the discussion with religious
references such as "devotion" "holy palmer's kiss." Romeo goes on in kind with similar
references such as "saint" and "prayer."

In all, Romeo is
comparing Juliet to someone just this side of heaven, to be worshiped and adored, as
pilgrims would worship a shrine.