It is true that children do tend to adopt the religion they learned about from their parents. In all other religions, one automatically becomes a follower by birth, by being baptized as an infant, or by observing certain religious practices. For example, a child is a Jew if born to a Jewish mother, or is considered a Mormon or Muslim if born into a Mormon or Muslim family. But one becomes a Christian only by personally repenting of his sins and placing his trust in Jesus Christ alone for his salvation. It is an individual decision, regardless of the religion practiced by the parents. Many people raised in other cultures decide to leave their religion and become Christians. God knows those whose hearts are truly seeking Him, and He ensures that they hear the gospel no matter where they are located. He can reveal Himself to people even in the midst of Hindu, Muslim, or animist cultures, so that they can put their trust in the Savior.
Also, keep in mind that believing something doesn’t necessarily make it true. Other religions are not equally true just because people were raised to believe them. Only Christianity is backed up by objective, historical, archaeological, and experiential evidence to verify that it is true.
1 Chronicles 28:9 “As for you, my son Solomon, know the God of your father, and serve Him with a loyal heart and with a willing mind; for the Lord searches all hearts and understands all the intent of the thoughts. If you seek Him, He will be found by you; but if you forsake Him, He will cast you off forever.