Explain to us then the rational opposing position then. Explain to us the pro-discrimination position whereby we should be permitted to discrimination on the basis of race, gender, age, or even sexual orientation when none of those things should matter.
You seem to be under the mistaken impression that all things except what the state have decided are proper should be forbidden.
Yes, among enlightened people race, gender, age, or even sexual orientation should not matter. That does not imply that unenlightened people should be subject to criminal prosecution or lawsuits.
You should be permitted to discriminate in some areas because you should be permitted to do anything you want that does not interfere with the fundamental rights of others. Housing is a fundamental right, so you shouldn't be legally able to discriminate in renting out a house. But hiring a specific person to take your wedding pictures is not a fundamental right, so a photographer should be legally able to turn down a paying customer for whatever reason they want, even bigotry.