Is the entire NT the holy word of God, to be believed by all Christians?
Now you just replace words NT -OT and Christians -Fariceies in your sentecse above and you will understand why they crussified Christ and what were feeling inside them. Sound similar? Can you see now what happens when one separates NT from OT?
So one could also truthfully say 'Is the entire OT the holy word of God, to be believed by all Pharisees?' and also "Is the entire NT the holy word of God, to be believed by all Christians?: And the answer would be yes in both cases.
Paul was a scholar of the OT scriptures, and a believing Pharisee who brought the good news of salvation through Christ Jesus to the Gentiles that was confirmed by the OT that was available at that time. This confirms that the OT and the NT should never be separated by presenting the NT better or worse than the OT. God gave us all scripture. Separating the words of the Father from His only Son is heresy, causing the truth to be distorted as did the hypocritical Pharisees during Jesus' time on earth. Those who separate the scriptures falsely are doing the same thing as the unbelieving hypocritical Pharisees.
The Pharisees who distorted the truth were those who were attempting to be righteous by their own works of the law without having faith in God who gave the law. It was both false religion and politics that led to the crucifixion of Christ. It is also false religion that kills the truth today.