To add more with regards to why I believe and know with complete certainty Islam to be the truth, an increase in knowledge and education, and scientific discoveries, provide further evidence that it is the truth. It is only right that if words are from the One who created the Universe, and nobody knows more about it then He, that those words should be in harmony with the workings of nature.
The enormously vast universe has been the object of curiosity since time immemorial. Greek philosophers, including Aristotle, believed that the Universe had always existed and would continue to do so eternally. This was also the mainstream view in scientific circles at the beginning of the 20th century, aptly known as the 'steady state theory'.
An eternal state of the universe meant that there was no inherent need for a Creator - for what does not have a beginning does not necessitate a need for a cause. However, advancements in science would shatter this view and fundamentally prove that the Universe had a beginning.
In 1922, physicist Alexander Friedmann, produced computations showing that the structure of the universe was not static and that even a tiny impulse might be sufficient to cause the whole structure to expand or contract according to Einstein's 'Theory of General Relativity'. George Lemaitre was the first to recognise the implications of what Friedmanm concluded. Based on these computations, Lemaitre declared that the universe must have had a beginning and that it was expanding as a result of something that triggered it. He also stated that the rate of radiation could be used as a measure of the aftermath of that 'something'.
The theoretical musings of these two scientists did not attract much attention and probably would have gone ignored except for new observational evidence that rocked the scientific world in 1929. That year, American astronomer Edwin Hubble, made one of the most important discoveries in the history of astronomy. He discovered that galaxies were moving away from us at speeds directly relative to their distance from us and from each other. The universe, long considered static, was expanding.
Stephen Hawking writes, 'The expansion of the universe was one of the most important intellectual discoveries of the 20th century, or of any century.'
Since the universe is constantly expanding, were we to rewind a film [of its history], then necessarily we would find the entire universe was in a joint state, referred to by some as the 'Primordial Atom'. Many scientists and philosophers resisted the idea of a beginning to the universe because of the many questions that it raised - primarily what or who caused it. However, with Penzias and Wilson's discovery of microwave radiation emanating from all directions, possessing the same physical characteristics - namely petrified light which came from a huge explosion during the first seconds after the birth of the universe - left little doubt about the fact that the universe had a beginning.
For fourteen hundred years, since the revelation of the Qur'an, Muslims had been reading and reciting the verses:
'the Heavens and the Earth were united [in a single state] and We tore them apart.' [21:30]
coupled with
'...the Heaven We constructed with might, and indeed, We are [its] expander.' [51:47]
Let's take mountains as another example (out of very many examples).
A book entitled Earth (1986, Frank Press and Raymond Siever) has been a basic reference textbook in many universities around the world. Professor Emeritus Frank Press was the Science Advisor to former US President Jimmy Carter, and for 12 years was the President of the National Academy of Sciences, Washington, DC. His book says that mountains have underlying roots. These roots are deeply embedded in the ground, thus, mountains have a shape like a peg.
This is how the Quran has described mountains. God has said in the Quran:
Have We not made the earth as a bed, and the mountains as pegs? (Quran, 78:6-7)
Modern earth sciences have proven that mountains have deep roots under the surface of the ground and that these roots can reach several times their elevations above the surface of the ground. So the most suitable word to describe mountains on the basis of this information is the word ‘peg,’ since most of a properly set peg is hidden under the surface of the ground. The theory of mountains having deep roots was introduced only in the latter half of the nineteenth century.
Mountains also play an important role in stabilizing the crust of the earth. They hinder the shaking of the earth. God has said in the Qur'an:
And He has set firm mountains in the earth so that it would not shake with you... (Quran, 16:15)
Likewise, the modern theory of plate tectonics holds that mountains work as stabilizers for the earth. This knowledge about the role of mountains as stabilizers for the earth has just begun to be understood in the framework of plate tectonics since the late 1960’s.
Nobody during the time of the Prophet Muhammad (peace be upon him) have known of the true shape of mountains, or imagine that the solid massive mountain which he sees before him actually extends deep into the earth and has a root. A large number of books of geology, when discussing mountains, only describe that part which is above the surface of the earth. This is because these books were not written by specialists in geology. However, modern geology has confirmed the truth of the Qur'anic verses.
These are just two examples. The Qur'an also talks about embryonic development, the origin of the universe, the cerebrum, seas and rivers, deep sees and internal waves, clouds, the water cycle and other facts, all proved true. And perhaps some not yet "discovered". As a result of these, a number of scientists embraced Islam by reading the Qur'an and realising that it was not from any human being, but from the One who created the universe.
The Qur'an, which was revealed fourteen centuries ago, mentioned facts only recently discovered or proven by scientists, and contains no scientific errors. This proves without doubt that the Qur'an must be the literal word of God, revealed by Him to the Prophet Muhammad (peace be upon him), and that the Qur'an was not authored by Muhammad (peace be upon him) or by any other human being. This also proves that Muhammad (peace be upon him) is truly a prophet sent by God.
The first word in the Qur'an, was an imperative ('Read!') addressed to the Prophet, linguistically immediately making the authorship of the text outside of Prophet Muhammad (peace be upon him). This is maintained throughout the Qur'an. It talks to the Prophet or talks about him, and does not allow him to speak for himself. The Qur'an describes itself (over 200 times) as a book that God 'sent down', conveying the concept that the Qur'an is from above and that the Prophet was merely a recipient. God is the one to speak in the Qur'an. The Prophet is addressed, 'O Prophet', 'O Messenger', 'Do', 'Do not do', 'They ask you...', 'Say', (the imperative form of the word 'say' is used in the Qur'an well over 300 times).
It supersedes the previous scriptures, while being a continuation, confirmation and culmination of the original message contained within them, in its last and final form. It has no versions or editions. Millions of people from all over the world have it memorised and they all recite word for word the same thing. There are no versions or editions, as there are with other scriptures. There is only one Qur'an. 100% God's word. Unchanged by any human. It's message is as applicable to the scientist in his laboratory today as it was to the Bedouin in the desert. It is as applicable to a man in a paddy field, as it is to a man in Silicone Valley. To everyone. People need to open their eyes, hearts and minds. To ponder and reflect, as the Qur'an encourages us to. The truth is clear. As it should be.
Peace.