I hope you can see that your premise here is not supported by the scriptures.
I'm afraid I don't see that, my friend.
It is clear that there is
someone who would not have killed Jesus had they known the mystery.
1Cor 2:8,
Which none of the princes of this world knew: for had they known [it], they would not have crucified the Lord of glory.
That someone is identified as the princes of this world. Why, whoever these folks are, would they have not killed Jesus?
First of all, we must know what this "mystery" is. It is not a matter of opinion or guesswork. The Bible is clear on what this mystery is. We can know it was hidden in God until He revealed it to the Apostle Paul.
Rom 16:25,
Now to him that is of power to stablish you according to my (Paul's) gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began,
Eph 3:3,
How that by revelation he made known unto me (Paul) the mystery; (as I wrote afore in few words,
1Cor 2:7,
But we (Paul & company) speak the wisdom of God in a mystery, [even] the hidden [wisdom], which God ordained before the world unto our glory:
Until it was revealed to Paul by God nobody knew this mystery. God's purpose in this mystery is clearly stated in Ephesians.
Eph 3:4-6,
4 Whereby, when ye read, ye may understand my (Paul's) knowledge in the mystery of Christ)
5 Which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit;
6 That the Gentiles should be fellowheirs, and of the same body, and partakers of his promise in Christ by the gospel:
Verse 6 states the end purpose of the mystery in clear terms. In the OT the Gentiles were without God and had no hope (Eph 2:12). The Jews were God's chosen people and the Gentiles were not His chosen people. I know that they could convert to Judism, but short of that they were flat out of luck when it came to salvation. It was quite an unexpected turn of events when God revealed to Paul that the Gentiles could now share fully with Israel. It probably fried the minds of many an Israelite when first revealed!
We saw in 1 Corinthians 2:7 that this mystery was ordained by God to our glory. That was nice of Him! What is the glory of the mystery?
Col 1:25-27,
25 Whereof I (Paul) am made a minister, according to the dispensation of God which is given to me for you, to fulfil the word of God;
26 [Even] the mystery which hath been hid from ages and from generations, but now is made manifest to his saints:
27 To whom God would make known what [is] the riches of the glory of this mystery among the Gentiles; which is Christ in you, the hope of glory:
Now I can understand why the devil would not have wanted a whole bunch of folks running around with Christ in them. That is pretty easy to see. Had he not killed Jesus, who being free from sin, would have lived forever (death comes by sin, Rom 5:12). The power of God to us is not in the crucifixion, but in the resurrection (it would be more appropriate for churches to have a picture of an empty tomb rather than crucifixes all over the place). It was the resurrection that allowed the plan of God to come into fruition. The devil had to kill Jesus in order for God to raise him from the dead. Once Jesus rose from the dead the mystery kicked in and it is Christ in me, Christ in you, and Christ in every born again believer. That was certainly not what the devil intended when he had Jesus killed!
The human leaders had nothing to lose by killing Jesus, but the devil had everything to lose. Why would Pontius Pilate have cared? He wanted nothing to do with the scriptures. Why would the Jewish leaders have cared? Wouldn't they have been more than happy to share their favor with God with the Gentiles had they known that was going to happen after Jesus died and rose as per the mystery? If not, why not?