It doesn't matter if it is right or wrong, what matters is if the both parties agreed to have sex before marriage or after the get married. Keep Christianity aside, I'm also a Christian too but I do not see any wrong if they both agree. One of the main reason why some people get married is because they want to have kids of their own, so those people will not want to end with a woman or a man that can not get them pregnant or a woman that isn't fetal. That is why I do not see any wrong in having sex before being married or after getting married.