Juliet shows that she is pure by not sleeping with Romeo until he marries her.
Juliet is fourteen years old, and when her parents talk about marriage she is only mildly interested.
Marry, that ‘marry’ is the very theme
I came to talk of. Tell me, daughter Juliet,
How stands your disposition to be married?
It is an honour that I dream not of. (Act 1, Scene 3)
However, when she sees Romeo at the ball she seems to be instantly attracted to him. However, she does not instantly go to bed with him. Instead, she insists on their getting married first.
Juliet knows that Romeo overheard her talking to herself in the moonlight. She does not want him to think she is “too quickly won,” but she knows he is already aware of her feelings have heard her innermost thoughts. She decides to throw caution to the wind, and vow her love to him.
Three words, dear Romeo, and good night indeed.
If that thy bent of love be honourable,
Thy purpose marriage, send me word to-morrow (Act 2, Scene 2)
Although Romeo and Juliet have only just met, they have a lot at first sight passion that cannot be quashed. They are utterly obsessed with each other, but Juliet remains completely chaste. She does not let Romeo any closer to her than the kiss.
Romeo and Juliet do get married through the church, by Friar Lawrence, but they do it in secret. By their society’s standards they have disobeyed their parents, and therefore committed a grave sin. Their actions certainly have consequences, since Romeo gets into a duel with Tybalt where he ends up killing him (after Tybalt kills Mercutio) and Juliet has to fake her own death with a sleeping potion in order to avoid a second marriage that her father has planned to Paris. Naturally chaos ensues, Romeo kills Paris, finds Juliet and thinks she’s dead, kills himself, so Juliet finds Romeo dead and kills herself.
In the end, Juliet’s purity did not do her much good. She was not honest with her parents, and Romeo was not honest with his. A little bit of honesty would have done these two young people a lot of good. It would have saved both of their lives, and the lives of Mercutio, Tybalt, and Paris. A little bit of wisdom and maturity would have saved a lot of lives in this case, and purity did not do them much good at all.