Final answer:
Christianity is the largest faith in the world, with approximately 2.2 billion followers. It is one of the key monotheistic religions, and despite increasing secularization, especially in developed countries, it maintains the highest number of adherents globally.
Step-by-step explanation:
Christianity is the single largest faith in the world, with an estimated 2.2 billion adherents. As a monotheistic religion, it recognizes a single supreme God and began 2,000 years ago in Palestine with Jesus of Nazareth. Despite its prominence, the level of religious commitment varies, with secularization affecting many Christians, particularly in the developed world. Christianity, along with Islam and Judaism, makes up the world's major monotheistic religions, having more than 3.8 billion followers combined. Among these, Islam is noted to be the fastest-growing and is projected to potentially have the most adherents by 2020. However, Christianity's widespread distribution still positions it as the largest faith. The presence and influence of different religions vary across the globe. In some regions, religious practices are deeply integrated into daily life, while in others, such as much of the developed world, religious fervor is not as pronounced. Nonetheless, a significant portion of the global population identifies with a particular religion or sect therein, with Christianity currently holding the position as the largest faith in terms of global followers.