For more than two billion people around the world, this Friday is Good Friday, the day Jesus Christ died for the sins of humanity.

For Christians from Western ChurchesThe Catholic and Protestant Churches celebrate Easter both use the Gregorian calendar, so they celebrate Easter at the same time. The Eastern or Orthodox Churches use the older Julian calendar, so their Easter is often different., it will be a day of church services, fasting and devotion. In Italy, statues and crosses in every Catholic church will be covered with a black or purple cloth. In JerusalemAn ancient city that is considered holy to Jews, Christians and Muslims alike., devotees will carry crosses to GolgothaAlso known as Calvary, this is the site outside the walls of Jerusalem where Jesus was crucified with two thieves. It now hosts the Church of the Holy Sepulchre., where they believe Jesus died. In the Philippines, some will even have themselves nailed to crosses to re-enact the suffering of their saviour.

In the secular, rationalist West, it is common to see Christianity as a slightly embarrassing relic of our history. Yet these celebrations go to prove that Christianity is alive and kicking in the world today. 

Almost one-third of the world is Christian, and the faith is growing rapidly in Africa and East Asia. A mere forty years after China relaxed its restrictions on religious beliefs, it already has the world's tenth-largest Christian community.

In fact, although we tend to think that the world is losing its faith, in reality, 84% of the global population identifies with a religious group, and this proportion is growing, not shrinking.

Clearly, much of the world still believes there are reasons to believe in God. But what are they?

MoralConcerned with what is right and wrong. compass. For some philosophers, belief in morality only makes sense if we also believe in God. Some suggest that it is improbable that morality could have developed in a godless world; it is simply not likely that so many people would have come to the same conclusions about right and wrong. Others argue that without God, we simply have no solid basis for any of our moral ideas.

Heavenly miracles. Many Christians believe they have had direct contact with the divine. Every day, people claim that they have been miraculously healed of an illness, or received something they prayed for. For them, the simplest explanation for these events is that God caused them. Miracles do not need to be big and showy: for some, the greatest miracle is the sense of fulfilment and purpose they get from their faith.

Cause and effect. The cosmological argumentA range of arguments all resting on the idea that the universe must have an origin, and the only possible cause is God. for God states that everything that begins to exist must have a cause. As such, the universe must have a cause, and according to this argument, this cause is God. The most common form of this argument today is the Kalam argument popularised by William Lane Craig. For some Christians, existence provides another form of evidence for God. They say the world is full of wonder, and simply to look at it is to see God's hand at work within it.

Trust in faith. But some think proposing "rational" reasons for believing in God defeats the point. God is the source of all things, including human rationality. Insisting on a rational basis for believing in God makes about as much sense as demanding a rational basis for believing in the existence of the world, or of human beings.

Yes: The vast majority of the world still believes in God, and they have solid reasons for doing so. Without God, it is impossible to explain so much of the world around us, as well as our own ideas about life. 

No: Whether we like it or not, science has ousted God. It has restructured our thinking around rationalism and empiricism and, in doing so, made God obsolete.

Or... Whether or not God really exists, it is clear that human beings are naturally spiritual creatures. Yet this aspect of our existence is obscured by both extreme rationalism and insistence on one specific God.