Reddit reviews Sex and the Soul, Updated Edition: Juggling Sexuality, Spirituality, Romance, and Religion on America's College Campuses

First of all, like others have said, ask her!! The topic of sex may make some Christians uncomfortable, but it's really important to be on the same page in relationships, and she'll likely appreciate the opportunity to explain her opinion on the matter. There are actually a lot of different perspectives on sex. Some stay chaste for life. Some think sex is inherently sinful, but needed to reproduce, and we'll be forgiven for it. Some think sex within the union of marriage is not inherently sinful. And some believe that premarital sex is okay too. Most Christian youths I've met believe that they should wait until after marriage to have sex, but I would venture to say that a third of them (or more) have had sexual experiences and will continue to engage in sexual activities before marriage despite holding this belief. So the lines certainly get really blurry.

I hope I don't offend you by saying this, but it's somewhat unusual for a Christian to be dating someone who's not religious because, as someone mentioned, 2 Corinthians 6:14 says that Christians should not be yoked together with unbelievers. I realize it sounds harsh, but for me personally, it rings true because my theology has profoundly impacted my personality, my interactions with others, my personal choices, my political beliefs, etc. This is NOT meant as discouragement! I'm only trying to elaborate on what others have said on the topic. For some couples, different religious beliefs have worked out okay. But it takes a lot of communication and patience. Another reason why I bring this up is that if she is dating an agnostic, she might have a different view on acceptable sexual activities before marriage than what I would consider to be those of mainstream Christianity.

So what is the view of acceptable sexual activity in mainstream Christianity? Generally speaking, many Christians would see vaginal sex, anal sex, oral sex, masturbation, mutual masturbation, and so on as unacceptable before marriage. Some may think that masturbation and oral sex are okay before marriage, but not vaginal sex or anal sex.

If you talk to her about these issues, try to avoid leading questions. What I mean by that is don't ask questions like "Do you think sex before marriage is morally wrong?" Ask questions like "What is your view on sex in relationships?" Listen to what she says and respect her decision. If she says she doesn't want to have sex before marriage, then as her partner, you need to help her do what she believes is right. If she says she is down for it, and you guys reach that point in your relationship, then great. Either way, support her.

On a side note, there are many different theologies concerning sex that I believe are valid even if they aren't compatible with my personal beliefs, so I understand what you mean when you say "depending on how Christian you really are," but the truth is, two very deeply religious and involved Christians can come to two totally different and well-informed conclusions on acceptable sexual activity before marriage.

I hope that this relationship has a positive outcome, whatever outcome that may be! I'll be happy to elaborate further on sex and marriage in Christian theology if you have any questions.

Also, here's a cool book on the topic if you're interested:
https://www.amazon.com/Sex-Soul-Updated-Sexuality-Spirituality/dp/0190221283