There's a lot going on in this thread. I'm going to share some more thoughts, since I have some time.
Especially to any girl who has been raped or been a victim of sexual abuse, or had lost her virginity at a young age. Honestly, I don't like these rings for those very reasons.
I tend to think of girls who have been raped or sexually abused as virgins still. I view virginity as something you get to give away, not something that can be taken from you.
I've known several girls who have been raped and sexually abused in general. I'm often the "safe guy" so I have had the opprotunity to be there for them and offer support. So I am very in tune with certain things that happen with them, thoughts, feelings etc. etc. I can say I don't know the first one who has a problem with someone wearing a purity ring.
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Now if someone is wearing the ring and also going around bragging and proclaiming to be better than everyone else, that is different. For all have sinned and fallen short of the glory of God. Also, pride comes before a fall. From what Kayla has said here, she's not doing that.
Also, I believe she certainly can wait. Which means there wouldn't be some awkward handing over of her ring to her Dad.
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It seems like a lot of Christians have the attitude of "Oh everybody messes up, everyone is going to fall in that area. Might as well just accept it". That is a terrible outlook and attitude to have. It's really relaxed and not taking sexual purity as seriously as it should be taken. Guess what? You CAN wait. It is possible. I'm 35 and by the grace of God I have waited on that. However, I have sinned plenty and can't say my thoughts etc. have always been pure. We are all sinners, BUT that is not an excuse to sin.
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I also believe those who have had sex outside of marriage can certainly be pure again. It just takes repenting. Repent means to not just say "I'm sorry Jesus" then do it again, but to really turn away from the sin and not do it again. Jesus certainly can cleanse and purify a person. He can and will wash away those past sins.
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I have known some who think they are less precious or valuable since they're not virgins anymore. That is SO wrong! Repent, let God cleanse you and don't worry. You're every bit as precious and valuable now as you were before. Don't let anyone tell you any differently.