I can't find any bible passage that specifically condemns premarital sex. But I have some understanding the nature of sex – it is best understood in relation to marriage eg "the two shall become one flesh" and "marriage is honourable in all, and the bed undefiled."
I am of a Baptist background – believing that 'rebirth' is baptism by the holy spirit, a personal experience one has, with baptism being purely symbolic and only to follow such a spiritual rebirth. I was baptised in the name of the Father, Son, and Holy Spirit at a fairly young age – I had had some degree of a spiritual rebirth beforehand, although I was very impressionable and the experience was largely emotional. As far as the water baptism went, I did not feel any different after than I did before it.
Now I'm looking into different denominations, and I'm trying to make sense of the doctrine of baptismal regeneration. Specifically I am wondering if a marriage/sex analogy would be helpful in understanding being 'born of water and of spirit.' Would it make sense to say being born of water, ie water baptism, is analogous to marriage in that they are both outward shows, celebrations even; and being born of spirit, ie 'actual" spiritual regeneration, is analogous to sex in that they are both very personal, intimate and unifying, one between man and God and one between man and woman?
I think sex should accompany marriage (love bears fruit) and spiritual renewal should accompany water baptism, but an analogy like this raise several questions, for instance someone I know was baptised at a young age because he and his parents thought he was 'Christian enough' but not until many years later did he actually have a spiritual awakening. Now he truly lives to please God – the change in his life was very obviously real and he considers himself unsaved after his baptism and up until that awakening he experienced. Should he get rebaptised?
Another example would be me – if the analogy holds well, my spiritual awakening before my baptism is akin to sex before marriage, but I knew shortly after the experience that I should get baptised. Just like any godly couple that does have premarital sex knows that marriage should shortly follow.
Another thing would be infant baptism. That would almost be analogous to an arrange marriage. I think arranged marriages can surely be a good thing.
Perhaps I'm way off base here.