Overall the concept of a God belief differs, based on experiences, theology, culture etc. With each individual the concept may deviate depending on that person's experiences, perspective and how they learned of a God to believe in. However, some God beliefs are more commonly shared within an organized religion, if you belong to one.

Consider a well known God, Jesus. When I hear this word, it means one thing to me. If a Buddhist hears it, it will mean something different. If a Christian hears it, it means something different. If an Atheist, something different again.

Subjective? An objective God belief, which exists, would mostly be shared and independent of perspectives, noted above.