As a 3rd generation born-in I mostly accepted the "reality" presented to me.
Doubts on birthdays, the generation, the anointed, and (spiritually) infantile "elders" were suppressed or rationalised.
Then one day the gospel was brought to my attention.
The more I pursued the gospel in their own publications the more I realised they don't in reality believe or teach it.
The clincher was the vitriolic contempt of the Pharisees ("elders") for the gospel in their own publications.