What does it mean to believe that Elizabeth II is the Queen?
A child may know that Elizabeth II is Queen of Great Britain. She may not, however, be aware that this makes her Queen of Australia, Canada, New Zealand, Jamaica, Barbados, the Bahamas, Grenada, Papua New Guinea, the Solomon Islands, Tuvalu, Saint Lucia, Saint Vincent and the Grenadines, Antigua and Barbuda, Belize, and Saint Kitts and Nevis, Head of the Commonwealth, the chief of state of Great Britain, the possesor of the residual prerogative powers, the head of the House of Windsor, formerly Saxe-Coburg Gotha, the fount of all honours, the Defender of the Faith, and the Supreme Governor of the Church of England.
Likewise, there are a number of things entailed by Jesus being the Christ, the Son of God. Some people believe some of these things while rejecting others.
The important question is, what is essential for a person to believe in Jesus as Christ and Son of God in a salvific way?