Aww the Jainism tenets looked great until they got to chastity. Why do so many religions and movements associate sex with sin? It is a beautiful, wonderful thing.
Before good birth control, extramarital sex meant single mothers. And if it's hard to be a single mom today, imagine being a single mom in a world where there were a fraction of the job opportunities outside the home for a woman.
It's not exactly with sin, but sexual activity is correlated with the power of creation. So "misusing" a "big bang" is often painted as something "bad", be it a sin or simply considered an act of layman's ignorance.
Brahmachary is often translated as chastity, but an alternate translation widely accepted in other spiritual traditions, like Bhakti, is fidelity within a committed relationship and conservation of sexual energy. So that might mean not masturbating every day, but conserving that sexual energy to bond with your partner (sexually or otherwise).
You sound like you're mocking it, and I almost didn't respond, but here goes (hoping you'll take this in good faith): people in the west like to nitpick on this, but you have to understand that Islam was born in an incredibly sexist environment where when your dad died, you could inherit your stepmothers as wives. Women weren't allowed to own property or inherit. So compared to that, Islam was incredibly progressive (women allowed to own businesses, inherit, entitled to all sorts of benefits in case of marriage, divorce, etc that simply did not exist before). So strictly speaking polygamy is allowed in Islam (man->women, not women->man) but that is not an obligation by any means. As times have changed, culture has changed, people have just stopped doing that as much.
I grew up in a conservative, Muslim-majority country and in my 18 years there, I did not meet a single person with multiple wives. I heard of one person though - a man from a village who worked in the city had one wife in each location. I never met this man, but a distant relative knew of him. That's it. Every other person I met was monogamous. I'm not trying to justify something you think is wrong, just giving you a bit of perspective that I hope you'll consider.
Your phrasing is curious. You're "not trying to justify something that [I] think is wrong." I would have removed the italicized section entirely. Do you not also think it is wrong that you have heard of a man with multiple wives but not vice-versa?
Saying "Christianity believes X" is likely to be not true for some denominations for any X other than "Jesus is the son of God"
Even if you restrict yourself to Protestantism in the US, you will have trouble generalizing too much; the doctrine of Sola Scriptura[1] is probably the only other universal there.
With regards to sexuality, there is very broad agreement that extramarital sex is sinful, but not much more agreement beyond that. Most protestants are accepting of contraception within marriage; Roman Catholic doctrine is opposed to any use of contraception (to the point of the official stance being that HIV positive married persons should never have sex rather than use a condom), however somewhere between "more than half" and 90% of western Catholics disagree with this.
James Dobson (A well known Evangelical Protestant psychologist) gets plenty of angry letters any time his stance that masturbation is a normal and healthy part of developing sexuality comes up.
They see sex as equally procreative and unitive -- so if you explicitly block either aspect, you're misusing it. (Catholic perspective, anyway, and probably significantly over-simplified).
Not sure why child post from aidenn0 is flagged dead, the way I read it it was correct and unoffensive but for what I know it might have been changed after flagging or I might have misread it.
Eh, I think there's a lot of room for progressivism out there. Problem is that a lot of Muslim-majority countries out there are very much in the dark ages, where the orthodox religious institutions have a chokehold on society, and that is what the world sees. If you actually go and observe Western muslim society (beyond newsmedia fearmongering), women are much much more so on equal footing here, and society thrives for it. I, for one, am very excited to see what direction this new generation of Muslim millenials in the West take the cultural development of Islam.
(based on my experience in the US; may not be true of Europe)
For Europe, at least where I am, it goes both way, in some parts the women are on equal footing to men, but in other parts it's the opposite, with women seen as inferior to men.