My answers to the poll question:
- No a potential juror should not be excluded due to race.
- No a potential juror should not be excluded due to ethnicity.
- Yes they should allow a potential juror to be excluded due to beliefs.
As far as I am aware, jurors are routinely excluded due to their beliefs.
If a potential juror in a trial of a drunk driver who killed someone had their child killed in the same way, they will most likely be biased against him.
If a potential juror believes all black persons are thieving rapists, they should be excluded from the trial of a black person who is accused of being a thief and/or rapist.
Beliefs are probably the most common reason for excluding a potential juror. If not the only reason.