The naive answer:
Christians are raised correctly. Non-Christians follow the religion they were raised in because they have not learned of Christianity.
The problem with the naive answer:
Most of the people of the world have learned of Christianity and very few raised in other religions such as Islam or Hinduism choose to switch. Learning about Christianity does not lead to conversion to Christianity.
The scholar’s answer:
People adopt the beliefs and cultures instilled in them by the families in which they are raised. This doesn’t happen all the time, but it does most of the time.
Food for thought:
Why is this a challenge for Christianity? Because it proves that people don’t adopt a religion because they believe it brings them closer to the truth, they adopt it simply because it is what those around them believe. It proves that Christianity has no more value to offer than any other religion, or than atheism. People will adopt a different religion when it helps them obtain a higher standard of material living, but for those who are well off, conversion is nearly impossible. Thus, it is easier to get people in Haiti to adopt Christianity (because the Haitians are poor and will do what they must to acquire food and shelter), but it is much more difficult for a Jehovah’s Witness to convert an American to being a Jehovah’s Witness because most Americans don’t stand to gain more material wealth by following the Jehovah’s Witnesses religion.
Logically, we can conclude that the primary determinant of a person’s religion is their parental influence. We know this from scientific research. This is true for every religion, or lack of religion. Therefore we can conclude that no religion, nor atheisms, provide such a significantly better approach to life than the other religions that most people will make a change. Due to this, we can also conclude that religions that promote more offspring will grow, as reported by Pew research PEW Religious Projections Through 2050.