I don't know that I "believed" it all as a walkaway but I do know I feared some of it was true. I had kept enough learned harmful attitudes and behaviors working in my life to make problems.
The fear that the world would end stayed with me long after I left. Many of the Watch Tower Corporation's teachings were presented to me to accept without proof. That fact made their claims difficult initially for me to disprove.
Another problem was the layered and fluid doctrinal package. I was not even really sure what I did believe as a Witness. Try to reduce the Revelation book to one paragraph. Or the blood medical guidelines.
In the end I went back and read the Watch Tower Corporation's publications starting with Three Worlds and all through Rutherford's rule. I studies word for word the Let God Be True book. That was the recruiting book as well as the study book in the 50's when I was indoctrinated.
After I learned the doctrines, I set about challenging them all with reality and facts.
That was where I did find out the right to question policy is not a policy but a teaching. When I initially had questions I asked the various Witnesses I knew and they dodged, lied and actually ran away from me.
Their behaviors actually convinced me they were practicing lying and deception by choice. And the teachings? They just melted like butter in the sun.