It really depends on what you mean by "popular".
All of the Christian movements combined in the world constitutes the religion with the largest number of members. At the moment 2.3 billion Christians make up about 32% of the worlds population. That's closely followed by Islam with about 23%.
So according to the numbers, Christianity is the most popular.
It has recently been observed that Christians are now the most persecuted people group in the world.
So according to society's reaction, Christianity is the most unpopular religion in the world.
I guess being popular isn't everything...
Yes, Christianity is the most popular religion in the world, with over 2 billion followers worldwide.
Christianity
Christianity.
Christianity
Christianity.
Christianity
The most popular religion is Christianity, accounting for just about 1/3 of the world's population.
The most popular religion in Zambia is Christianity. The Zambian constitution recognized Christianity as the official religion in 1996.
Christianity.
Christianity
Christianity I hope.
Worldwide, that would be Christianity.