When I was in Saudi Arabia, I was friends with a Saudi,
who was helping me to learn Arabic.

He was also using the Koran, as a textbook.
He was trying to convert me to Islam.
I read the entire Koran.

Instead of relying on my impressions on that book,
read it for yourself; and, ask yourself these questions:

1. Is this Koran the word of God laid out simply, in a
straightforward manner?

2. Are these ramblings, which either:

a. relate to an issue that was currently
affecting the messenger (prophet), and
often served his personal interests; or,

b. repeat again and again and again
(sometimes with significant variations)
the messenger's views on the universe,
Biblical stories, or how Allah and his host
will treat believers and unbelievers?

3. Why would God repeat himself,
and vary his word on any topic?  
Did God forget, that he already addressed an issue,
did he think of a better way to make his revelation; or,
were variations made by the messenger,
as he retold yarns from his imagination?

I pointed out a few inconsistencies in the Koran
to my Arab friend.  
He didn't talk about them, instead pointing out errors
in the Bible, such as events after the birth of Jesus:

In Matthew 2:14 Joseph to fled to Egypt, after an angel
warned him to keep baby Jesus from being destroyed by King
Herod; however, at the same time,

Luke 2:21 said that, after eight days, baby Jesus was
circumcised, and taken for purification in Jerusalem,
then finally to Joseph's home in Nazareth of Galilee.

My Arab friend was right, there were many hundreds
(if not thousands) of discrepancies in the Christian bibles;
but, only dozens of contradictions in the Koran.
However those few dozen contradictions in the Koran
might seem to be so significant, that one could question:

"Does Allah, as defined by the Koran, even exist?"; and,

"Is Islam is one of the worlds great religions; or,
the worlds biggest cult?"