Alright, first off I believe that Islam is true based off a lot of reasons. Reason number one is that if you study the history of pre-islamic Arabia you will see that the arabs going from a barbaric way of life of just bedouins living in a desert that even the persians and romans viewed as useless land and useless people thats why they had no interest invaiding them, to having some of the biggest empires, it in a sense exploded in a fast time and being influential to even modren day things like how the Islamic golden age contributed to many things we currently have as a result of it, alone this is a miracle. Reason number 2 is that Islam covers all aspects of life including law notably in 1935 the usa supreme court honoured our Prophet Muhammad (PBUH). It's not subjective to time and it gives as morales something that in my opinion many atheists and agnostics can't really decide. The third reason is that it includes falsifiable claims such as the Quran challange and that the book will be preserved as Allah commanded. The fourth reason is that there is no contradiction with the modren day. The fifth reason is that I believe in God because I cannot comprehend the idea of the cosmos not being created by a higher power. when you see a building, you know there was a archtitect, so why do you suppose nothing could have produced a world as beautiful as the one we live in? Those are some reasons I thought of right on the spot, ill add on the list but those are pretty big ideas.