Again
How in the world does the GB of Jehovah's Witnesses presume know that less than 1% of the millions of those martyred for the name of Christ from Pentecost to the start of the 20th century were real Christians?
Because they require a basis for their absolute authority. A way of being "brothers" without actually being equal? Watchtower is a religious apartheid organisation. The rulers and the ruled.
Watchtower is a legalistic organisation that changes over time not with well thought out, reasoned principals in order to make the lives of it's adherents - and the world - better, but in a reactive way. In order to patch up the gaping holes that appear in their patchwork of ideas with the passing of time.
Example: only 144,000 will go to heaven. Initially a way for his followers to feel 'special' when the end didn't arrive in 1914 (or 1897, 1899, 1925, 1975 etc etc) and Russell passed away, Rutherford as his heir required an explanation for the increase in numbers and - most importantly - something that gave him the authority the founder had. Thus The Filthful Slavebugger The faithful slave was born.