If there is one thing that never ceases to frustrate me about the WTS it is the way they love to twist scripture to suite their needs. The "Light getting brighter has always been one such verse that made me wrinkle my nose and shake my head.
When reading the verse in-context, it's obvious that the intend of the scripture has absolutely nothing to do with revealing or refining truths as the end draws near.
The path of the righteous is like the morning sun, shining ever brighter till the full light of day.
But the way of the wicked is like deep darkness; they do not know what makes them stumble. (Prov. 4:18-19) (NIV)
I firmly believe that if more people read through their cherry picked scriptures in their entirety, there would be more seeds of doubt planted in the minds of those still in.