You may want to try out one of a number of empirical implicit bias tests at https://implicit.harvard.edu/implicit/takeatest.html

These tests have been administered to large numbers of people and on average, almost every single person that has taken the test has scored some level of implicit bias. As a result, it's very likely (but not certain) that you ARE unaware of your implicit bias.

Of course, if you take the tests and score perfectly, you'll now be able to demonstrate empirically that you have no measurable implicit bias and will have an answer to those people who insist you do.

The reason why this is different to the walking on water statement, is that there are hundreds of thousands of data points all showing implicit bias is almost universal, whereas there are zero data points showing people can walk on water after believing in Jesus.