Why would this be hard to prove? The FBI has kept these statistics for years.
A quick search came up with this. https://www.usnews.com/news/articles/2016-09-29/race-and-homicide-in-america-by-the-numbers
Read and think about how many more Whites live in America than blacks.
The statistics show that the 500 killings of white people attributed to blacks last year were the most since black perpetrators were determined to be responsible for the homicides of 504 white people nationwide in 2008. Last year's total was up 12 percent from the 446 recorded in 2014 and 22 percent from the 409 seen in 2013, a year that saw the lowest total this century and one that capped seven years of general declines in black-on-white homicides. Prior to that, 2006 saw the most black-on-white killings since 2001, with 573.
The 229 black lives taken by white killers last year, however, marked an even larger leap from 2014, jumping more than 22 percent from the 187 black victims killed by whites that year, which was the second-lowest total since 2001. The tally was last exceeded in 2008, when 230 blacks were slain by whites. The highest total in the last 15 years came in 2007, when 245 black people were killed by whites.
I'm not saying you shouldn't have concealed carry in a church, that much seems to be advisable nowadays.
You say this like it's indisputable fact. I won't change an existing belief like that without some evidence. That said, it's going to be damn hard to prove either side of that one. The absence of evidence does not prove the point, though.