Černobog (black god) and Belobog (white god) are recent „inventions" of some neopagan rodnovery fractions. Slavic pantheon knows no ewil god or god of ewil. Chernobog has some atributes of Veles and Belobog some of vise Stribog. Also, it is good to know that slavic pantheon have several...
The attitude is everything :) I am Serbian and speak six slavic languages but cant connect your „arguments" with the quotation. Facts are (by all researchers and old historians) that slavic beliefs are based on their descending from old gods.
Not exactly true story and position in pantheon (slavic pantheon „organisation"is quite different from greek) but good text all the same.
http://www.slavorum.org/perun-slavic-god-of-thunder/
Now is 7525th year in Slavic calendar. Counting is based on few monuments remaining from prechristian times and few records of russian origin. It is reputed to be a count from „the beginning of the world".
https://en.m.wikipedia.org/wiki/Jaromarsburg
There is a record of one of the last temples. Soma call Arkona „the holy mount of Slavs" comparing it to Athos in Greece.