Atheists and Agnostics frequently make statements to the effect of:
This article will discuss why these statements are distortions and misrepresentations of reality, with the goal of dissuading a person from seeking absolute truth.
This is the breakdown of what the world believes, according to a 2015 study published by Pew Research:
Adding these up reveals that approximately 93.3% of the people on earth believe in either no religion, Hinduism, Buddhism, Islam, or Christianity.
Going further, Buddhism was started by a former Hindu, who kept the fundamental doctrines of Karma and reincarnation from Hinduism. And, Islam claims to be a successor to Christianity, which affirms the God of the Bible. So, there are basically two groups - Dharmic religions that believe in Karma and the cycle of reincarnation, and Abrahamic religions that affirm the God of the Bible.
Beyond these two major groups, there are other religions, of course - no one is disputing that. However, very few of them have so much as a scripture, or an organized, and identifiable "orthodox" set of beliefs, or even a dedicated following who singularly follow it alone, rather than engaging in a high degree of syncretism. And, often the number of adherents is vanishingly small, relative to the world's population, and isolated to a single people group or geography.
I study comparative religion as a hobby, and I have spent quite a bit of time investigating whether there is any little-known religion that is actually extremely compelling, historical, and robust. There is not. Feel free to do your own research. I believe you will quickly come to the same conclusion.
In Christianity, we have Scripture which contains prophecy, and we have the resurrection of Jesus Christ. No other religion has anything close to those two proofs when it comes to making a case to someone who is seeking the true religion from the God whom all human beings know made us and our planet (Romans 1:20, Psalm 19:1).
Similarly, there aren't that many denominations within Christianity. Just as above, a person can categorize into broad groups, and use prayerful, reasoned study to come to a conclusion.
Both of these critiques - there are too many religions, and too many denominations - engage in the same logical fallacy - that because the truth is contested, it cannot be known. That's not true, of course. Everyone knows it's not true. This is just an alibi appealed to by those who are not genuine about seeking absolute truth with all their heart (Hebrews 11:6).
The idea that the God of the Bible is "one of many", or that there are a host of competing religions that all seem equally compelling to a sincere, intelligent enquirer, is false. Such a thing can only be stated by someone who has never actually bothered to study comparative religion, or what these "thousands" of religions teach, claim, and consist of.
Just because the truth is contested does not mean that it is unknowable. A person can find the truth, and pray for God to guide them in that search - and He will (Revelation 22:17).