As of the early 21st century, Christianity has approximately 2.4 billion adherents. The faith represents about a third of the world's population and is the largest religion in the world. Christians have composed about 33 percent of the world's population for around <answer>100 years</answer>. The largest Christian denomination is the Roman Catholic Church, with 1.17 billion adherents, representing half of all Christians.
How long have Christians made up nearly 1/3rd of the population?
100 years