God chooses an honest and trustworthy person to deliver His message to Mankind, and makes him a perfect example of religion so that, with his words and deeds, he guides mankind towards God.
The Prophet is the best and most perfect of all human beings. In knowledge, manners, and behavior, he is the foremost of all mankind, and God has cultured him and chosen him to be for people a leader and an example.
The Prophet knows very well the path to happiness in this world and in the Hereafter,... because God has taught it to him. The Prophet treads this path himself and he invites people to tread the same path and leads them on it.
The Prophet knows God well and loves Him very much.
He is perfectly aware of the situation in the Hereafter, and in Heaven and Hell. Good and bad morals and actions he recognizes perfectly. He sees the ugliness and foulness of sins and knows that sin pollutes the human soul.
God, the All-knowing and Almighty, has put this vision and awareness at the disposal of His Prophets. With this vision and awareness, the Prophet sees the ugliness and foulness of sin and knows that God doesn't like wrong-doers and is displeased with them. For this reason the Prophet never commits a sin; rather, he is disgusted by sin.
The Prophet delivers God's messages to mankind without additions or deletions and without mistakes or forgetfulness.
Because the Prophet is without sin and mistakes, people rely on him and can take example from his words and from his deeds, and can benefit from his supervision and leadership.
Such a person is called infallible (ma'sum) and God's Prophets are all infallible. That is:
They do no wrong, they neither make mistakes nor forget, they are perfectly honest and trustworthy.
Prophets are the aware and sinless guides of mankind.
They deliver God's message to their people, guide them, and lead them towards God and eternal happiness.
source : http://www.maaref-foundation.com
