Every Rasulullah (messenger of Allah) is a Muslim, but what does "Muslim" mean, and so, do you fit the definition or description of Muslim? Do you have the 2 basic attitudes or characteristics of Muslim? And fundamental belief: Do you believe that Allah is our creator, our lord, our king, our god? Be honest. And dare to ponder. Don't be deceived regarding the meaning of worship and god and Muslim and Islam. And make no mistake regarding the meaning of slavery and liberty and shirk and tauhid (tawheed) and "najis".
How did Rasulullahs, including Muhammad and "Jesus Christ", become Muslims? In short, Muslim means one who surrenders to Allah. And a Muslim is necessarily one who worships Allah, only Allah. If you want to become a true Muslim, or if you want to have a good relationship with Allah, then enliven or put to practice, "oh Allah, my creator, my god, only you are my lord, my king, and to you I surrender; salaam, oh Allah, salaam". Hard? Do the right thing! Hmm, so many "ulama" are teaching the wrong way of becoming Muslim. And verily, the "Syahadah" should be regarded as a false "pillar" of Islam. Be rational. And be righteous.