The entire Quran talks about Muslims; it does not talk about any Sunni or Sunnatul Jamat Muslim.
Let’s check whether there is a prefix or a suffix to the word Muslim in the Quran.
3:95 Say (O Muhammad SAW): “Allah has spoken the truth; follow the religion of Ibrahim (For the similar verses refer 6:161, 4:125, 2:135)
2:130. And who turns away from the religion of Ibrahim except he who has engaged himself in foolishness.
3: 67. Ibrahim was neither a Jew nor a Christian, but he was a true Muslim Hanifa.
Based on the above verses, one should be proud to announce oneself as a Muslim, but not as a Sunni Muslim. Ibrahim (Alayhi-salam) was a Muslim. Muhammad (Sallallahu alaihi wasallam) followed his religion; he was a Muslim, a Prophet, and a Rasool to mankind.

