Does God revealing spiritual truth to us mean we have no free will or that God predestined us to hell or heaven?
No. God revealing spiritual truth by opening our understanding does not take away free will, nor does it mean God has bound us to a decision to go to hell or heaven. God must open our understanding so we can comprehend spiritual truths, but free will remains.
Les teaches from the context that flesh and blood did not reveal spiritual truth to Peter, but the Father in heaven did. This shows that we cannot comprehend spiritual truths unless God opens our understanding. Yet Les explains that this divine opening does not take away our free will, and it does not make us bound to a decision by God that we are going to go to hell or to heaven. Before we can comprehend spiritual truths, God has to open our understanding, even as Jesus said God did with Peter. That divine revelation enables spiritual comprehension, but it does not cancel human free will or force a predetermined destiny to heaven or hell.
And Jesus answered and said unto him, Blessed art thou, Simon Barjona: for flesh and blood hath not revealed it unto thee, but my Father which is in heaven.