Steve was born on an island. Isolated and alone, with no signs of human activity or development. He was brought up to an age in which he is just capable enough to rely on himself and the local resources. His birth parents have seemingly disappeared and is now the only inhabitant, sharing with other species on a small land mass.
In this scenario and skipping ahead a decade or so, the lone islander would not share the same faiths as the rest of the world for the same reason he also wouldn’t speak English, Spanish or Chinese. It’s has to be taught.
On an island with no understanding of science everything is mysterious. From the sunrise behind crashing waves to the stars after sunset. The world has had a God to help explain almost all phenomena and natural process throughout our history and it is highly likely Steve would invent a similar way of thinking to help comprehend his reality. If we were to find Steve on the island, would he be practicing Christianity? Or looking up to the sky speaking to Allah? Of course not.
A symbol such as a cross would mean nothing on the island, as there would be no logical reason to assume so. It is an easy symbol to stumble upon when walking through branches or sand for instance, especially considering how we seek such patterns to reassure us of our faith. Various and apparent symbols left by chance and nature could then be attached to a new belief.
Similar to evolution, a religion would take a totally different path when isolated from other beliefs. This is why today we have multiple religions, now clashing in a better connected world. We are told that God has infinite wisdom and power, yet it is only after being influenced by others within a society that we accept a religion. Not a personal connection with God. When we hear on the news of a tribe coming into contact with outsiders for the first time, it is almost a certainty that the religion or ritual practiced is completely unique.
This is a fantastic example of a challenge to the idea that religion is more than chinese whispers passed down over millennia. It merely takes isolation to take out a whole ideology.