My Questions for Muslims That No One of Them is yet to Answer by Musa

Evang. Musa M.B (Left), Evang. Ibrahim Dikko (Right)

I am asking Muslims these questions for the second time and this post is not meant to criticise Islam and Muslims.....please take note!

Dear Muslims, I have heard enough of this saying that all Prophets are Muslims including Isah (Jesus).

Again, for one to convert to Islam, he has to say the 'Khalimatus Shahada' that is, "Asshadu Allah ilaha illahu wa'ash hadu Anna Muhammadan abduhu wa rasuluhu". Meaning, "I bear witness there is no god worthy of worship except Allah. And Muhammad is the servant and prophet of Allah". 

With due respect, my questions are as follows:

1). If the name of Muhammad is included in the Khalimatus Shahada, then all the prophets from Adam to Isah (Jesus) were not Muslims because, during their time, Muhammad was not born. 

2). If the prophets were Muslims as the Qur'an insists, how did they become Muslims when the Khalimatus Shahada was not introduced during their time?

3). How did Muhammad (himself) become a Muslim when the Khalimatus Shahada includes his name?

Please I need your answers!

Evang. Musa B. M.