As difficult as it can be, I actively resist calling any person a "racist".

If I call another person a racist, it puts the burden of racism on the other person and makes it a lot easier for me to dismiss any racist attitudes or beliefs or behaviors that I have and struggle with. This reinforces my own privilege and hence, does not really help in the struggle for equality among humans.

It also incapsulates an entire person based on one characteristic (regardless of how deplorable that characteristic may be). In turn it limits the imagination from presenting an alternative for that person.

If it's a person's behavior I am calling out and challenging, there is more opportunity to process through and make some sort of progress toward and ideal end (less racism).

If it's a person I am calling out, they are more likely to take it as an attack and strengthen their defenses, which is counter productive.

To put it much simpler and eloquently: Hate the sin, not the sinner.