There are so many cute guys at school who aren't Christians. My mother keeps saying I need to date only Christian guys. What's the big deal? Why is it so bad about dating non-Christian? It's not like I'm going to marry one or anything!
You have a natural, God-given attraction to the opposite sex. You will have many choices of boys when you view them from the physical side. There may be many cute guys out there, but what is the most important aspect of your future date?
When you put a white flower into a vase of water that has some blue food colouring in it, the flower will gradually take on a bluish hue. When you choose the company of non-believers you are in danger of taking on their ideals and morals. You may soften, dilute or disregard what you know is right.
Everybody has a god that they live by. Who will be the god of your life? Will He be the God of the Bible or the god of today's culture?
As Christians we strive to take on the characteristics of Jesus: "Love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control” (Galatians 5:22-23). Won’t you want your date to share these same characteristics as you? Non-Christians may have different goals, strive for different things and hold different things important in their lives. You will be unequally matched. The differences may seem small at first but as you become more certain of your path, those differences will become huge. And these will be the source of conflict, disagreements and heartaches.
Your mother's words are wise and godly. She is looking out for your happiness and well-being. God designed relationships. He loves you and knows you. Trust Him to bring a Christian young man into your life, who will be your match. Two are stronger than one. God desires you to find the strength in a partner who will share the same values as you. This will make you both stronger. And together, God will use you to bring His love to others.
See also 2 Corinthians 6:14.