The alternative to tolerance is unanimity, at least on certain principles. It requires everyone to have identical interpretations of ostensibly basic concepts such as justice (if two groups differ in their views on what is just, one can believe that justice is present while the other does not). Unanimity comes with drawbacks. It is difficult to achieve given a large enough group. Once achieved within the group it makes anyone who dares to challenge it (either from inside or outside of the group) acutely hated. And it decreases the diversity of available opinions on which evolution-like forces can act (so as to progress human understanding).
Tolerance might be a pretty terrible solution, but it’s better than all the other ones we have invented so far.