My girlfriend and I have been together for eight months now and have been discussing about having sex. We do plan on getting married because we are both loyal, honest and love each other very dearly. However, we both have very strong religious backgrounds and are not sure if we could be forgiven if we do have sex. My top question is: if we do has sex and we get married like we plan, will we be forgiven of our sexual sin? We need help on this journey because we both fear of losing the other over something that can be avoided if it is a sin.
One of the characteristics of a Christian is their aversion to sin. "No one who is born of God practices sin, because His seed abides in him; and he cannot sin, because he is born of God" (I John 3:8). This doesn't mean a Christian doesn't sin at times, but it does mean that a Christian doesn't make a practice or habit of sinning. Sin is just not something a Christian wants in his life.
When a Christian does sin, we can be forgiven of the sin if we repent on that sin. But that doesn't mean that because we know that forgiveness is available that we can purposely set out to sin. "What shall we say then? Shall we continue in sin that grace may abound? Certainly not! How shall we who died to sin live any longer in it?" (Romans 6:1-2). When a Christian does sin, God does offer forgiveness, but it is based on our repentance. "For godly sorrow produces repentance leading to salvation, not to be regretted; but the sorrow of the world produces death. For observe this very thing, that you sorrowed in a godly manner: What diligence it produced in you, what clearing of yourselves, what indignation, what fear, what vehement desire, what zeal, what vindication! In all things you proved yourselves to be clear in this matter" (II Corinthians 7:10-11). Repentance comes from our regret at our sin. It means we have a change of mind about the sin and a change in our behavior.
But notice how none of this fits with what you are planning. You aren't seeking to avoid sin. You're planning to sin. You plan on continuing to do it until you get married. Yes, once you are married having sex is no longer a sin, but it doesn't erase the fornication you commit before marriage. That sin is still there. You have no regrets about this sin, so, therefore, there is no repentance. Though we don't want to consider this, what would happen if either of you died while you are involved in this sin? "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" (1 Corinthians 6:9-10). I know you plan to get married, but even that is not guaranteed. "Come now, you who say, "Today or tomorrow we will go to such and such a city, spend a year there, buy and sell, and make a profit"; whereas you do not know what will happen tomorrow. For what is your life? It is even a vapor that appears for a little time and then vanishes away. Instead you ought to say, "If the Lord wills, we shall live and do this or that." But now you boast in your arrogance. All such boasting is evil" (James 4:13-16).
This is why the writer of Hebrews warned about willful sin, such as what you plan to do. "For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins, but a certain fearful expectation of judgment, and fiery indignation which will devour the adversaries" (Hebrews 10:26-27). It isn't that such sins could not be forgiven. The problem is that people who deliberately plan on sin, as you plan, will not turn from their sin. Yes, you plan to eventually stop sinning, but you would justify it to yourselves.
If you want to have sex and can't wait, then the answer is simple: get married! You say you plan to marry anyway, so moving up the date doesn't make much difference. "But if they cannot exercise self-control, let them marry. For it is better to marry than to burn with passion" (I Corinthians 7:9). Make your planning energy productive by planning to do righteousness instead of wickedness.
I would like you to read a few articles on why sex is for the married: