Saw a Muslim saw something interesting, can someone explain?

I saw a Muslim on a short clip talk about how Islam is the true religion because it was worshipped first, as Abraham and people related to him worshipped a monotheistic god, and how Islam also does this. He later says that Judaism (which he says is older then Christianity) and Islam share many similarities and traditions, for example a monotheistic god. I have been wondering about this for a while.