And mix not truth with falsehood, nor conceal the truth [i.e. Muhammad Peace be upon him is Allâh's Messenger and his qualities are written in your Scriptures, the Taurât (Torah) and the Injeel (Gospel)] while you know (the truth). (2:42)

Allah has opened his message in a plain manner, so do not try and mix good with bad, why?

As we know today, every individual tries and keeps himself, and when he or she finds some time, then thinks about worshipping.

People always look for improvements in any small or big thing during the duration of one's life, for example, people set goals for themselves, or there children, to go from kindergarten to university. All efforts are put in one's life, in order to have improvements, but when it comes to religion, when a person has time he would practice like cattle, meaning without thinking about Allah, the creator, sustainer, and provider for everyone.

When it comes to matters related to Islam, everything worldly should be considered as secondary.

"nor conceal the truth"

This means, that Allah gives us an example of the Jews, Christians, and those Muslims who know the truth, but avoid it in order to tell others, and are shy because they are scared of loosing there status in society, and whoever sits down and thinks deeply about his creator, provider, and sustainer, he or she would know immediately what Islam is, Islam is represented by the Prophet Muhammed, Isa (Jesus), Musa (Moses), Abraham, and others who were sent by Allah, they all have the same message not to worship idols, and do not seek intercession from anyone, but worship Allah alone, who is the Provider, Creator, and Sustainer for everything.

Once we see the other books, the question would raise to the non-believers (kaafirs), or those who Muslims who do not practice, when they glance the Qur'an, it looks like the message is kind of similar to the bible, or the Torah, the same basic message, not to lie, cheat, steal, murder, etc. But the difference between the Qur'an and the other books is, the Qur'anic verses are protected by Allah. If one would go to any museums in major cities, one can find handwritten Qur'an. And today if one would go anywhere in the world, whether in Africa, or places such as the United States, or anywhere else, we cannot find a single dot changed from the original. Satan gives us the idea, that if we talk about the truth of Islam, we will look outdated.

The ignorant point, is that the people of the book know the truth, but they are not ready to accept it, because of there excuses, of status, society, and many more. Whatever law they like the follow, but whatever law which stops there things which are prohibited, when it comes to there enjoyment of prohibited things, they find excuses not to agree and follow it. Likewise, we could see those who call themselves as Muslims, but are not willing to adopt the laws of Islam, whatever  they could follow, they follow, with the excuse that society, and culture cannot be left behind for Islamic law, and in there minds they are under the impression, that they do not want to look outdated.

Another fact is, because new versions are always being introduced of the bible, with the excuse of explanation, and a new improved version of the bible. In order to generate more business, with different titles, explanations, and thousands are available in the market.

"[i.e. Muhammad Peace be upon him is Allâh's Messenger and his qualities are written in your Scriptures, the Taurât (Torah) and the Injeel (Gospel)]"

Now one could see the life of the Prophet Muhammed , before age 40, the character he had amongst the Makkans, he never lied, cheated, and was called Al-Amin (meaning the trust worthy) by the Makkans. Even during his Prophecy, while he was spreading Islam, and they all were enemies to him, but still use to keep there valuable things in his trust. He was also a problem solver for them, so therefore they knew the truth, but hid it. That time or today, people know the truth, but avoid following it, and telling others.

In the past, Allah mentioned about all of the important Prophets in previous books, and Allah also mentioned the Prophet Muhammed , why?

First of all, Allah knows best about the future, in order for the people of the book to transfer the message to the next generation, of the Prophet Muhammad's coming. So when the Prophet Muhammed comes, people should accept without "but" or "why", once we spend our lifetime towards research for every small material, such as physics, chemistry, and many other fields, so what is stopping us to compare the notes of the Prophet Muhammed , who is the most important Prophet, because he is the last messenger of Allah, and his message from Allah will be applied until the last day of the world, so why are we ignoring it?