How are the rules unjust? What threat of force? The Bible is God's word, so how is that religion imposing limitations?
First of all, we have only the word of Christianity that the Bible is "God's word," and that is a highly dubious assertion for many reasons. Secondly, the assertion is self-aggrandizing as it works to augment the power of authorities within the Christian religion.
Third, in effect it is a demand that people believe, under threat of force (and the answer to what that is remains, as stated before, "Hell"), ideas that seem to the logical application of thought, to the available concrete evidence, and to the fruits of spiritual experience itself, to be false.
The demand that we believe something that appears to all reliable evidence to be false, in furtherance of the aggrandizement of the power of a priesthood, under the threat of force, is unjust.