Q. I am a high school student. Is it a sin for me to have lustful thoughts for my girl friend even if we’re not going to do any thing until marriage?
A. In Matt. 5:29 Jesus said that anyone who looks at a woman lustfully has already committed adultery with her in his heart. (He could have applied the same standard to women looking at men.) He did this to show that sin begins in our desires, whether we act on them or not. His purpose was to dispute the belief held by the religious teachers of the day that if they didn’t act on their sinful desires they hadn’t sinned, and to show that since it’s impossible to avoid having sinful thoughts, every person is a sinner who needs a savior.
Therefore, it is a sin to have lustful thoughts about your girlfriend. But if you have accepted the Lord as your Savior, and if you confess your sins, the Lord is faithful and just and will forgive your sins and purify you from all unrighteousness (1 John 1:9).