Does Unity teach that only through a Christian belief can one go to Heaven?
No…Truth is Truth wherever it is found, and the journey of awakening or enlightenment isn’t limited to a follower of the teachings of Jesus. It is much like learning that 7 times 7 is 49 within a Christian setting, or is made by someone sitting in the outback using stones to discover the principle of multiplication. God (Principle) doesn’t “care,” and God (Principle) has unlimited “patience” as humankind remembers that in Truth they are Godkind.