To you it has been given to know...

[Ladodgers6]

If people are born without the ability to see the truth, as Calvinists believe, again, why the need to "hide" anything... they CAN'T see anyway.

Because this is how our Lord chose to speak. But both hear the same message, right? So, why do God's sheep hear the message and believe, while the others do not believe.

Answer is found in John chapter 10:

22 At that time the Feast of Dedication took place at Jerusalem. It was winter, 23 and Jesus was walking in the temple, in the colonnade of Solomon. 24 So the Jews gathered around him and said to him, “How long will you keep us in suspense? If you are the Christ, tell us plainly.” 25 Jesus answered them, “I told you, and you do not believe. The works that I do in my Father’s name bear witness about me, 26 but you do not believe because you are not among my sheep. 27 My sheep hear my voice, and I know them, and they follow me. 28 I give them eternal life, and they will never perish, and no one will snatch them out of my hand. 29 My Father, who has given them to me is greater than all, and no one is able to snatch them out of the Father’s hand. 30 I and the Father are one.”

So, here you have it, right out of the mouth of Jesus. The Pharisees asked Jesus if He was the Christ. Jesus replies, saying, I told you and you do not believe. Why don't they believe? Because they are not among His Sheep. Then He brings this home by saying that His Sheep hear His voice and follow Him.

These Pharisees were face to face with the living God telling them who He is. And yet they do not believe.​