Religion and science are poles apart. It is nonsense to say that they complement each other. Religion is based on 'divine revelation' and faith, while science is based on reason and observation. I believe that men should be governed by science.
Religion says that there is a supernatural being called God, who is permanent, immortal and all powerful. Science holds that there are no supernatural entities like God, angels, fairies, demons,witches or soul ( and therefore there is no such thing as transmigration of the soul, or resurrection on Judgment Day ), and that nothing is permanent, everything is changing, and in a state of flux, in accordance with certain laws which can be discovered by scientific research.
Science holds that the only reality is matter, which is in motion according to certain laws.
Some people ask : who created matter ? The answer is : there is no creator of matter. Matter came from matter, though the form keeps changing.
With every step science advances, religion recedes. Thus, people at one time thought that small pox is due to the anger of a goddess ( mata ), but now we know it is because of a virus, and can be prevented by innoculation. People at one time thought that rains are caused by a rain god, Indra, and so if there is drought we have to propitiate that god in some way ( many people in India still believe that ). Today we know that rains are caused by the build up of low pressure areas over a heated land. People at one time believed that Adam and Eve were created by God. Later Darwin proved that men evolved from the apes.
Why is religion such a powerful force even today ? It is because of massive poverty in the world and the feeling of helplessness. Religion gives a solace, an imaginative respite, to the poor masses who are living in utter misery. Without such a temporary respite they may go mad, so horrible are their lives.. And as for people who are not poor, they too often take recourse to religion in view of the uncertainties in life.
For example, businessmen too are often religious, because there are uncertainties in business, and so they take recourse to god to save them from any business calamity ( I was told that some prosperous businessmen in the south have gifted some shares in their companies to Balaji, the God of Tirupati, and the dividends go directly to Him). The amount of ' chadhawa '( offerings ) in many temples is enormous.
People take recourse to religion ( as they take recourse to astrology ), because of a feeling of helplessness. They plan something, but something else happens. In other words, we are unable to control our lives. So we believe that it is some supernatural force ( or, in the case of astrology, the stars and planets ) which control our lives ( hoi wahi jo Ram rakh rakha ).
The truth is that we are unable to control our lives because of the low development of science as of today, compared to what it will be 100 or 200 years hence. In that future age, science will have developed so much that we cannot even imagine about it today, and then men will be able to largely control their lives, and then there will be no need of God.
The scientific outlook took a long arduous struggle to gain acceptance. For centuries the Church in Europe persecuted the greatest scientists with blind ferocity, hounding them, torturing them and burning them at the stake. Bruno was burnt at the stake. Galileo almost met the same fate during the Inquisition, and escaped only by recanting ( Copernicus' theory ). Even as late as 1925, a teacher in U.S.A. John Scopes, had to face a criminal trial ( the famous 'Monkey Trial' ) for teaching Darwin's Theory of Evolution ( see online ).
It is said that many scientists believed in God. That only proves that scientific and unscientific ideas can co-exist in the same head. Since originally most ideas of men were unscientific, their remnants will persist for a long time, often in men who are otherwise quite scientific in their thinking.