O son, praise be to Allah for making us Muslims, Alhamdulillah but who do we prove ourselves to and how do we prove ourselves that we are Muslims?
Know that everytime you proclaim the 'letting go' phrase:
La hawla wala quwata illah billah hil 'Aliyil 'Azim
There is no power and no strength, save with Allah, the High, the Great; Allah responds to you, saying: "My servant becomes a Muslim. My servant submits himself to me."
Now, what better acknowledgment can you hope for, if not that? For Allah to accept you as Muslims!
La hawla wala quwata illah billah hil 'Aliyil 'Azim.
"There is not a moving creature, but He has grasp of its forelock. Verily, my Lord is on the straight Path." (Surah Hud 55-56)
So, submit to Him, O son, submit yourself and be a Muslim!
Reference: Shaykh Hisham Kabbani, Friday Khutbah, Cyprus 3rd July 2009.