I took it upon myself to correct the corrector, and the Editor found my answer to his question so illuminating, he insisted I prepare it for publication in the Times. Below you will find the results of those efforts. I hope you all find my article enlightening, at some level or another.

This question of what religion is the most populous -- not necessarily popular, just which one has the greatest number of proponents -- is a tricky one.

Christianity, Judaism, and Islam are all related. These religions recognize prophets from the others, so they are more or less harmonious -- not that current events would lead you to expect that!

The Hindu and Buddhist religions are also closely related. There was a fairly good description of this at the Norton Simon Museum (in Pasadena, CA) early in 2001. The Buddhist religion apparently appeared first, and later was incorporated with traditional folk gods and belief systems in India to evolve into the Hindu religion. Of course I may have totally misunderstood the exhibit at the Norton Simon, in which case I'm completely wrong. :-)

There are many other religions that you didn't mention -- such as Shinto in Japan. There are also prominent non-religious philosophies such as Confucianism, which is quite prevalent in Chinese and Korean culture.

The question of which is most populous is complicated by the number of sects in each religious sphere. The Christians are split into Catholics, Protestants, Baptists, etc. Islam is split into Shi'a, Sunni, Sufi, etc. Ditto for other main religions.

The most populous countries are India and China. China doesn't have an official religion. India is about 85:15 Hindu:Muslim. This suggests that Hindu may by the most populous single-country religion. Worldwide, however, Christian and Islamic recruitment has been the most aggressive. I already know that Islam is not the most populous worldwide religion, which then suggests that Christianity is the most populous. It would be nice to have more data on this issue.

The real puzzle with this question, though, is that many people who follow the cultural implications of a religion may not actively pray, attend church, or even believe -- yet, for example, they celebrate Christmas by exchanging presents and believe that adultery is a crime. Are these people Christian? Do you include them in your tally? Ditto for other countries: who's really practicing and who isn't? Of those who don't practice, how many pseudo-religious cultural traditions do they need to observe or you to count them as holding the same value system anyway? If people are forced to attend church -- through peer pressure or oppression -- but don't believe, how do you adjust your count? Thus gray areas quickly arise and it's difficult to correct.

I would welcome any hard data that is available on this; however, I suspect that only subjective data exists. If you'd like interesting data on a particular country, try the CIA World Factbook at www.cia.gov/cia/publications/factbook/index.html.

I suppose one could use an electoral college model, just like the U.S. states do for electing a President, and have the most populous religion in a country swing the entire country. Using this method, you could arrive at a clear winner. However, one can quite easily mathematically prove that the electoral college method could elect a winner with less than the most populous votes worldwide, just as happened in the most recent U.S. Presidential election.

So, what do you really want to know? How precise are you willing to make your question? How many more questions will you have to answer before reaching a plausible conclusion for your original speculation? That's what it comes down to.