In school , we are taught the religion of humanity and to accept every other faith with tolerance.
For practising Muslims , the religion of humanity is Islam , and tolerance means maintaining peace with all faiths unless someone unjustly oppresses you.
A true Muslim , follows the verses of the Quran and the way of life of Prophet Muhammad (peace be upon him) rather than follow his own ideas and beliefs.
Why not always follow whatever our self and intellect say ?
Some questions :
What is the purpose of human life ?
Why are we here ?
When we die ......what happens later ?
Each one of us will answer differently or similarly.
Human intellect is limited.
For someone who observes the universe and everything in it , will ultimately have to conclude that a Creator has to exist for the creation.
And each created thing has a 'purpose'.
Examples are all around us.
Ponder on the following points :
Islam is not a man-made religion.
The Quran , is a direct conversation of God ( Allah as He taught us of Himself ) to humankind.
It is the only scripture in the world whose text (Arabic) is unchanged , word-to-word , since its revelation in the 6th century and remains preserved in the hearts of Muslims who have memorised all of its 30 parts.
Allah has sent prophets from the beginning of the world's creation to teach mankind about His existence and to worship Him alone.
Allah says in the Quran :
" And I did not create the Jinn and mankind except to worship Me… "
Those who believe , do righteous deeds will be able to see Him on the Day of Judgement and be rewarded ( Heaven or Hell ) according to their 'marksheets' of the test in this temporary worldly life.
Prophet Muhammad was the last prophet sent to all mankind ; with his prophethood , Allah completed the code of life He decreed for human beings to follow until the Day of Judgement.
Now , it is every Muslim's duty , to tell people about Allah.
I shall quote some translated verses :
" Then do they not reflect upon the Quran ? (i.e. its meanings and its objective) If it had been from [any] other than Allah, they would have found within it much contradiction. "
The Quran is available for scrutiny and investigation by any person to try to find even one error or contradiction in it. In fact this test must be applied to any other scripture that claims it is the word of God.
In other words...there is every means in it to call man to use his LOGIC.
" Indeed, in the creation of the heavens and the earth and the alternation of the night and the day are signs for those of understanding - Who remember Allah while standing or sitting or [lying] on their sides and give thought to the creation of the heavens and the earth, [saying], “Our Lord, You did not create this aimlessly; exalted are You [above such a thing]; then protect us from the punishment of the Fire.”
" And whoever desires other than Islam as religion - never will it be accepted from him, and he, in the Hereafter, will be among the losers (in the Hellfire). "
Lastly , 'there is no compulsion in religion'.
Allah has left man with a free-will......to believe or disbelieve.
And He has sent plenty of proof ( logical , scientific , practical ) in the Quran , in the life and character of His last prophet ; in everything around us.
We , Muslims , are merely instructed to preach .....not force anything down anyone's throat.
For further information :
Best way to find the truth is through knowledge.
The knowledge is present in the Quran as well as the life history of the man who was an illiterate and recited such a masterpiece that stunned the Arabs of his time and continues to do so even in this day.
(3) Dr. Zakir Naik is an Indian , world famous scholar who has studied various scriptures (Hinduism included) and written books which will benefit the seeker of Truth.
An example : CONCEPT OF GOD IN MAJOR RELIGIONS
He hold lectures too ...inviting non-Muslims to voice their doubts etc.