Should I keep dating my girlfriend?

Isn't this between you and your girlfriend? I don't understand why you would care what this minister (or us random people on the internet) think. As long as you are honest with each other, what's the problem?

If a couple consists of a believer and a non believer, why does the minister suppose the influence is always one way? Who is to say that a believer's piety and faith cannot influence their faithless partner for the good?

A belief that crumbles when it is exposed to the real world is not worth having. Hey! Wait a minute! You said you aren't religious and you only go to church (twice a week!!!) to please your mother, and you worry about what a "youth minister" says? Maybe you aren't the big atheist you think you are?

1 Corinthians 7:13-14

If any woman has a husband who is an unbeliever, and he consents to live with her, she should not divorce him. For the unbelieving husband is made holy because of his wife, and the unbelieving wife is made holy because of her husband. Otherwise your children would be unclean, but as it is, they are holy.

You said,
"so a believer will end up not being strong in their faith if they date a non believer".

This is not true as I myself have dated women who are unbelievers and my faith remaind strong infact in one relationship my faith grew even stronger. The more you get closer to God and understand the significance of the blood of Jesus Christ the more you understand love and forgiveness which really are the essence of Christianity. It really depends on your faith. Remember Christianity is not a religion...it's a relationship, a relationship you have with Christ, a relationship you have with God.

One thing I have come to know about God is that he works in mysterious ways. You said you used to be religious, maybe God wants you to rekindle your faith and that is why he has partnered you up with a woman of faith. Maybe it's you who "will end up acting like whoever your in a relationship with"?.

Don't let your girlfriend go. When the knocks on your door, make sure you let him in. It will be the wisest thing you'll ever do!!