I sent my girlfriend a nude picture and I want her to acknowledge it.
Is there a particular way that you want your girlfriend to respond to the picture?
I'd want her to entertain me and send me the same sort of picture back immediately.
While there are people in relationships that enjoy sending explicit text messages to one another, it's not something that everyone is comfortable with doing. If your girlfriend doesn't reciprocate sending explicit messages, it's a sign that she is uncomfortable with that behavior and it's inappropriate to press her to change. While it's good that you find your girlfriend to be physically attractive, you should find other ways of getting attention that do not make her feel uncomfortable.
God says you should submit to your man and it's expected.
Your girlfriend is her own persona and doesn't have to submit to anyone and definitely not by sending nude pictures to you. Her boundaries and comfort levels might differ from yours and as her partner, it's something that you should respect and support.