Marrying an agnostic man

I am a practising Muslim woman and I want to ask if I can marry a Muslim agnostic man. He lives by sunni school of thought, had a Muslim upbringing, is a Muslim on paper and doesn't indulge in anything haraam. He however, is struggling with the knowledge of Allah Ta'ala. He doesn't deny His existence but he says that he hasn't found a proof of Him as well. We both want to marry each other but I want to know if our nikaah will be valid or not?

Note: Agnosticism is different from Atheism and I hope that I made his beliefs clear.