Rev. R. Bosworth-Smith:

"Head of the State as well as the Church, he was Caesar and Pope in one; but, he was Pope without the Pope's pretensions, and Caesar without the legions of Caesar, without a standing army, without a bodyguard, without a police force, without a fixed revenue. If ever a man had the right to say that he ruled by a right divine, it was Muhammad, for he had all the powers without their supports. He cared not for the dressings of power. The simplicity of his private life was in keeping with his public life.
"His readiness to undergo persecution for his beliefs, the high moral character of the men who believed in him and looked up to him as a leader, and the greatness of his ultimate achievement all argue his fundamental integrity. To suppose Muhammad an impostor raises more problems than it solves. Moreover, none of the great figures of history is so poorly appreciated in the West as Muhammad... Thus, not merely must we credit Muhammad with essential honesty and integrity of purpose, if we are to understand him at all; if we are to correct the errors we have inherited from the past, we must not forget that conclusive proof is a much stricter requirement than a show of plausibility, and in a matter such as this only to be attained with difficulty." Muhammad at Mecca, W. Montgomery Watt, Oxford press, p. 53

K.S Ramakrishna Rao, an Indian Professor of Philosophy in his booklet, Muhammad, The Prophet of Islam, calls him the: "Perfect model for human life."
Prof. Ramakrishna Rao explains his point by saying:

"The personality of Muhammad (pbuh), it is most difficult to get into the whole truth of it. Only a glimpse of it can I catch. What a dramatic succession of picturesque scenes! There is Muhammad (pbuh), the Prophet. There is Muhammad (pbuh), the Warrior, Muhammad (pbuh), the Businessman; Muhammad (pbuh), the Statesman; Muhammad (pbuh), the Orator; Muhammad (pbuh), the Reformer; Muhammad (pbuh), the Protector of Slaves; Muhammad (pbuh), the Emancipator of Women; Muhammad (pbuh), the Judge; Muhammad (pbuh), the Saint. All in all these magnificent roles, in all these departments of human activities, he is like a hero."

Michael Hart in The 100, A Ranking of the Most Influential Persons in the History, New York, 1978, p. 33:

"My choice of Muhammad (pbuh) to lead the list of world's most influential persons may surprise some readers and may be questioned by others, but he was the only man in the history who was supremely successful on both the secular and religious level. It is probable that the relative influence of Islam has been larger than the combined influence of Jesus Christ and St. Paul on Christianity. It is this unparalleled combination of the secular and religious influence which I feel entitles Muhammad (pbuh) to be considered to be the most influential single figure in human history."

M.K Gandhi, statement published in Young India, 1924:

"I wanted to know the best of the life of one who holds today an undisputed sway over the hearts of millions of mankind... I became more than ever convinced that it was not the sword that won a place for Islam in those days in the scheme of life. It was the rigid simplicity, the utter self-effacement of the Prophet, the scrupulous regard for pledges, his intense devotion to his friends and followers, his intrepidity, his fearlessness, his absolute trust in God and his mission.
"These and not the sword carried everything before them and surmounted every obstacle. When I closed the second volume (of the Prophet's biography), I was sorry there was no more for me to read of that great life."

Sir Bernard Shaw in The Genuine Islam, Singapore, Vol. 1, No. 8, 1936:

"If any religion had the chance of ruling over England, nay Europe within the next hundred years, it would be Islam."