How do I help a person who wants to get married but is against premarital ?

Why do you need to 'help' someone who is against premarital ? Friendship, trust and respect are all much bigger parts of a marriage. If they don't believe in before marriage, there is nothing wrong with it. At least he/she will be able to discover the joy of once they are married and have something to look forward to. If a marriage is based on alone then it doesn't stand much of a chance of surviving. Let them believe what they believe and allow them to live their life as they chose.