Premarital sex is in conflict with the Word of God. “But fornication and all uncleanness or covetousness, let it not even be named among you, as is fitting for saints;” (Ephesians 5:3 NKJV)
And lest we think that fornication is of no afterlife concern, we must refer to 1 Corinthians 6:9-10. “Do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived. Neither fornicators, nor idolaters, nor adulterers, nor homosexuals, nor sodomites, nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners will inherit the kingdom of God.” Simply put, unrepentant fornicators will not spend eternity in heaven. The matter is that serious.
While the spiritual concerns are of the utmost importance, I want you to consider another important aspect of the issue. That being, premarital sex is a destructive force that could destroy your future marriage.