1. Bible: Send a Bible as a birthday present, so that my girlfriend can learn more about Christian teachings and principles on her birthday, thus deepening mutual understanding and feelings.
2. Cross or icon: If your girlfriend believes in Christianity, you can consider sending a cross or icon as a birthday present to show your support and respect for her faith.
3. Music or poetry: If your girlfriend likes music or poetry, you can consider sending some related music albums or poems as birthday gifts to express your support and appreciation for her hobbies and interests.
4. Books or movies: If your girlfriend likes reading or watching movies, you can consider sending some related books or movies as birthday gifts to express your concern and support for her spiritual life.
In short, when giving a gift to your girlfriend, you should consider her beliefs and hobbies and respect her personal wishes. Don't let the gift become a formal expression, but really let her feel your love and care.