Sex before marriage is a very serious sin, both in the Old Testament and in the New Testament.
In some cases, depending on the specifics of the situation, it was a capital offense, meaning it was to be punished by death. Whoredom, adultery and rape all carried the death penalty. Thus, those who engaged in sexual relations with someone other than their spouse, they were to be put to death. You can find the relevant texts in Leviticus, chapters 20-22.
However, in the case of an unmarried man convincing an unmarried woman to have sex with him the penalty was not death, but either a great financial cost and marriage, or a greater financial cost, depending on the decision of the woman's father. There is no difference in the penalty depending on the method the man used to entice the woman. The marriage was not to be postponed, but the price paid and the marriage sealed as soon as the father of the woman dictated. The relevant texts can be found in Exodus 22 and Deuteronomy 22.
