Islam is what all people were supposed to follow since Adam (the father of mankind) was created. All mankind should worship
God and follow His instructions. Every time most people forgot and disobeyed, God had sent a messenger to renew their faith.
All messengers believed the same things we believe now despite minor changes in rules or religious proceedings.
The final message of Mohammad (PBUH) has been protected by God and will remain till the day of doom, therefore details
of this message should be the guide to mankind.