
Now, with that said, I'd like to start by saying you can't judge Islam based on the actions of Muslims. In every group there's a bad bunch - just like there are Christians who beat their wives, or drink or do bad things - that doesn't mean that Christianity itself is at fault... likewise, Islam is not to be faulted for the bad actions of those claiming to be followers.
So what does Islam mean? Islam by definition means to submit, surrender and obey in peace and sincerity to the will of God - anyone who does this is a Muslim.
It also means you believe in only one God, and Muhammad (peace and blessing be upon him) is the last and final prophet of God (Allah) - ending the long line of noble prophets before him, Noah, Abraham, Moses, David, Solomon, Jesus, etc... (peace and blessings be on them all).
Muslims believe in God, the Creator, the Sustainer of all the universe. We don't believe in a sun god, or a moon god. We believe in The One and Only, God - which translated in Arabic is Allah.
We also believe in the sacred texts which have been revealed - essentially known as the Bible - the Torah, the Psalms, the Gospel. However, these texts have been changed by man and are no longer in their original form - and they have many errors and inconsistencies. God is perfect and His word is perfect - these texts are not and can no longer be considered the words of God.
However, God revealed the Qur'an and the Qur'an has been protected and has remained intact, never changed - not even a letter, for more than 1400 years. If I could chose one verse which proves to me that the Qur'an is from God - it would be the following verse:
"Man We did create from a quintessence (of clay); Then We placed him as (a drop of) sperm in a place of rest, firmly fixed; Then We made the sperm into a clot of congealed blood; then of that clot We made a (foetus) lump; then we made out of that lump bones and clothed the bones with flesh; then we developed out of it another creature. So blessed be Allah, the best to create!"
Al-Mu'minun 23:12-14
It was not until the 20th century that scientists have confirmed our bodies are made up of every element found from the earth/ground/dirt. The Bible also talks about man being created from clay/dust/dirt... however, God gives further explanation in the Qur'an and gives details about how the embryo is formed in the uterus. Science has confirmed the stages of the development of an embryo/baby in the uterus and the descriptions found in the Qur'an coincide with those stages.
There is no way possible for a man more than 1400 years ago to just make that up. That "information" came directly from the Creator alone. Of course there is much more that makes me believe in the Qur'an - but if I had to pick one example - this would be it.
Therefore, I follow the teachings of the Qur'an as they have been preserved and protected and not changed by man - so they remain the true Word of God.