Unsaved Loved Ones

I've been more and more concerned lately about most of my family not being saved. Not sure why, but I find myself thinking and praying about their salvation more and more. Especially my sisters. My mom and dad know the Truth, they both were raised in the church, they still read their Bibles occasionally, and in their hearts I'm pretty sure they still believe. Kim, Heidi, and Kelly are another story. I've tried so hard to witness to Kelly, to help her understand. I let her keep my old teen Bible for a while and then for her birthday Ed and I bought her her own. I know she hasn't made the decision yet though, and I wish so badly she would. I can't imagine going to Heaven one day and not finding my family there. Just the thought of it is heartbreaking. And even though I know that the decision is up to them, I still feel responsible, as the only Christian in the family, to help lead them to Christ. I don't know what else to do though. Kelly acts almost as if it's some sort of fairy tale, and that she has a long time to make up her mind. Kim just flat out doe not believe any more; she'll talk about it at least, but she's convinced that all religions are out-dated and false. Heidi is down-right hostile to talk about Jesus--she refused to speak to me for months that time a few years ago that I sent her a forwarded Christian e-mail (it was really just a cute story). I know I need to just keep praying--"pray without ceasing"--and keep looking for opportunities to share with them all that my faith means to me. It just makes me feel so uneasy though, and so sad, knowing what they're missing.