When an individual pronounces the testimony: "Ash-hadu allaa ilaaha illallaah wa ash-hadu anna Muhammadar- Rasullullaah" (I testify that there is no god worthy of worship except Allaah and I testify that Muhammad is His Messenger), believing in it and acting upon it, he experiences a noticeable change in his life.
By understanding who his Lord is as well as the purpose of his creation, he will be able to achieve success in this life and the next. This success emanates from the following points:
1- A believer in this testimony can never be narrow in outlook. He believes in Allaah, Who is the Creator of the heavens and the earth, the Master of the universe and its Sustainer. After this belief, he does not regard anything in the world as a stranger to himself. He looks on everything in the universe as belonging to the same Lord he himself belongs to. Allaah Almighty Says (what means): "Say (O Muhammad): 'To whom belongs all that is in the heavens and on earth?' Say: 'To Allaah.'" [Quran 6:12]
His sympathy, love and service are not confined to any particular sphere or group. His vision is broadened, his intellectual horizon widens, and his outlook becomes as liberal and as boundless as is the Kingdom of Allaah. How can this width of vision and breadth of mind be achieved by an atheist, a polytheist or one who believes in a deity supposed to possess limited and defective powers like a man?
2- This belief produces in man the highest degree of self-respect and self esteem. The believer knows that Allaah Alone is the Possessor of all power, and that none besides Him can benefit or harm a person, or provide for his needs, or give and take away life or wield authority or influence. This conviction makes him indifferent to, independent on, and fearless of all powers other than those of Allaah. He never bows his head in homage to any of Allaah's creatures, nor does he stretch out his hand before anyone else. He is not overawed by anybody's greatness. This attitude of mind cannot be produced by any other belief.
3- Along with self-respect, this belief also generates in man a sense of modesty and humbleness. It makes him unostentatious and unpretending. A believer never becomes proud, haughty or arrogant. The boisterous pride of power, wealth and worth can have no room in his heart, because he knows that whatever he possesses has been given to him by Allaah, and that Allaah can take away just as He can give. In contrast to this, an unbeliever, when he achieves some worldly merit, becomes proud and conceited because he believes that his merit is due to his own worth. In the same way, pride and self-conceit are a necessary outcomes and concomitants of 'Shirk' (association of others with Allaah in worship), because a polytheist believes that he has a particular relation with deities, which does not exist between them and other people.
4- This belief makes man virtuous and upright. He has the conviction that there is no other means of success and salvation for him except purity of soul and righteousness of behavior. He has perfect faith in Allaah Who is Above all needs, is related to none and is absolutely Just. This belief creates in him the consciousness that unless he lives rightly and acts justly, he cannot succeed. No influence or underhand activity can save him from ruin.
As to those who do not believe that there is any Being having power over them, to whom they should be responsible for their good or bad actions; therefore, they consider themselves independent to act in whatever way they like. Their own fancies become their gods and they live like slaves of their wishes and desires. Allaah states in the Quran (what means): "Have you seen he who has taken as his god his [own] desire, and Allaah, knowing (him as such), left him astray, and has set a seal upon his hearing and his heart, and put over his vision a veil? So who will guide him after Allaah? Will you not then remember?" [Quran 45:23]
5- The believer never becomes despondent. He has a firm faith in Allaah Who is The Master of all the treasures of the earth and the heavens, Whose grace and bounty have no limit and Whose power is infinite. This faith imparts to his heart extraordinary consolation, fills it with satisfaction and keeps it filled with hope. Although he may be met with rejection from all sides in this world, faith in and dependence on Allaah never leave him, and on that strength he goes on struggling. Such profound confidence can result from no other belief than belief in Allaah Alone.
Atheists have small hearts; in the sense that they depend on limited abilities; therefore, in times of trouble they are soon overwhelmed by despair and, frequently, they commit suicide.
The testimony of Prof. Joad is also very explicit on this point. He writes about the West: "For the first time in history there is coming to maturity a generation of men and women who have no religion, and feel no need for one. They are content to ignore it. Also they are very unhappy, and the suicide rate is abnormally high." [C. E. M. Joad. The Present and Future of Religion, quoted by Sir Arnold Lunn., And Yet So New, London, 1958, p. 228]
As to the world of Islam, let the views of a non-Muslim historian, not in any way being sympathetic to Islam, be read with profit:
"In this uncompromising monotheism, with its simple and enthusiastic faith in the supreme rule of a transcendent being, lies the chief strength of Islam. Its adherents enjoy a consciousness of contentment and resignation unknown among followers of most creeds." [Suicide Is Rare in Muslim Lands] (Phillip K. Hitti, History of the Arabs, 1951, p.129)
6- This testimony of faith inspires bravery in man. There are two things which make a man cowardly: (a) fear of death and love of safety, and (b) the idea that there is someone else besides Allaah who can take away life, and that man- by adopting certain devices- can ward off death. Belief in 'Laa ilaaha illallaah'' blocks and drives away both these ideas. The first idea goes out of his mind because he knows that his life and his property and everything else really belong to Allaah, and he becomes ready to sacrifice his all for the pleasure of Allaah. He gets rid of the second idea because he knows that no weapon, no man or animal has the power of taking away his life; Allaah alone has the power to do so. A time has been ordained for him, and all the forces of the world combined cannot take away anyone's life before that time.
It is for this reason that no one is braver than the one who has faith in Allaah. Nothing can daunt him: not even the strongest tempest of adversity and the mightiest of armies.
7- The belief in 'Laa ilaaha illallaah' creates an attitude of peace and contentment, purges the mind of jealousy, envy and greed, and keeps away the temptations of resorting to base and unfair means for achieving success. The believer understands that wealth is in Allaah's hands, and He apportions it out as He Wills; that honor, power, reputation and authority - everything - is also subjected to His Will, and He bestows them as He Wills; and that man's duty is only to endeavor and to struggle fairly.