Allah Says in the Qur'an in the interpretation of the meaning:

"Let there be no compulsion in Religion: truth stands out clear from error: whoever rejects evil and believes in Allah (one God) has grasped the most trustworthy hand hold, that never breaks. and Allah hears, and knows all things." 
(Qur'an, Al-Baqarah 2:256)

Islam is not a new religion, but the same truth that God revealed through all His prophets to every people. God tells us in the Qur'an:

"Say: we believe in God and in what has been revealed to us, and what was revealed to Abraham, Isma'il: Isaac, Jacob and The Tribes, and in (the Books) given to Moses, Jesus and the Prophets, from their Lord: We make no distinction between one and another, among them, and to God do we bow our will (in Islam)." (Qur'an, Al-'Imran 3:84)

For a fifth of the world's population, Islam is a complete way of life encompassing all facets of a Muslims existence from birth to death:

"This day I have perfected your Deen (Complete way of Life, Religion) for you, and completed my favour upon you, have chosen ISLAM as your Deen (way of life)." (Qur'an, Al-Ma'idah 5:3)

As Muslims, we give the message of Islam to mankind, the evidences and facts and invite them to accept Islam or to reject it.

"Let there be no compulsion in Religion: truth stands out clear from error: whoever rejects evil and believes in Allah (one God) has grasped the most trustworthy hand hold, that never breaks. and Allah hears, and knows all things." (Qur'an, Al-Baqarah 2:256)