First of all, thank you for your valuable and detailed solutions for the problems.
My problem is I am a Christian and my boyfriend is not a Christian, but he believes in Jesus. We were committed through some sort of sexual immortality a few years back. We want to marry each other as soon as we get in good jobs. My mother who knows we are in love, but doesn't know we are commited and want to marry, says I can't marry someone who is not in God's will, and if you do so, you have to face a lot of problems. I cannot marry another as it consider as prostitution to keep someone in heart and marrying another. I am stuck between having committed sexual immortality and my mom's words that it's not God's will.
Please help me in my situation.
As you realize, committing acts of sex when you are not married are acts of sin. "Marriage is honorable among all, and the bed undefiled; but fornicators and adulterers God will judge" (Hebrews 13:4). I hope that such sins continue to remain in the past. But in addition, you need to correct your error by repenting of your sins (II Corinthians 7:10-11) and apologizing to God for breaking His laws (I John 1:9).
Because you sinned with a man, it does not mean you are obligated to marry him.
Who you decide to marry is your decision, not your mother's. Your mother is correct that a Christian marrying a non-Christian faces many problems in life. Your husband will not understand a greater devotion to God than his own. He'll want you to skip church services and do things that would not be appropriate for a Christian. You've already seen a bit of this when he convinced you to have sex, even though you knew that fornication was a sin. Things will get more difficult after you have children. He'll want to raise the children as he believes and you will want to have them follow your beliefs. However, if you want to live with these and other difficulties, that is your decision. It is not a sin to marry a non-Christian. "But to the rest I say, not the Lord, that if any brother has a wife who is an unbeliever, and she consents to live with him, he must not divorce her. And a woman who has an unbelieving husband, and he consents to live with her, she must not send her husband away. For the unbelieving husband is sanctified through his wife, and the unbelieving wife is sanctified through her believing husband; for otherwise your children are unclean, but now they are holy" (I Corinthians 7:12-14).
Thank you, brother, it means a lot. It cleared many doubts.