Bible Verses about “not trusting”

“It is the spirit who gives life. The flesh profits nothing. The words that I speak to you are spirit, and are life.”

“But there are some of you who don't believe." For Jesus knew from the beginning who they were who didn't believe, and who it was who would betray him.”

“Therefore many of his disciples, when they heard this, said, "This is a hard saying! Who can listen to it?"”

“But Jesus knowing in himself that his disciples murmured at this, said to them, "Does this cause you to stumble?”

“Then what if you would see the Son of Man ascending to where he was before?”