Many people, instead of enjoying the pasture, huddle around the gate attempting to keep people out. In the Gospel of John, Jesus compares salvation to stepping through a door, presenting Himself as that door. He says that we, like sheep, can find pasture if we go through the door.
John 10:9
I am the door: by me if any man enter in, he shall be saved, and shall go in and out, and find pasture.
Once you are saved, you will always have access to the pasture. You can always find food, drink, and rest for your soul.
John 4:14
But whosoever drinketh of the water that I shall give him shall never thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting life.
John 6:35
And Jesus said unto them,
I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst.
But there are many who don’t want you to be saved; and if you are saved, they don’t want you to rest. They may claim the name of Jesus, yet they preach prerequisites for salvation.
Matthew 23:13
But woe unto you, scribes and Pharisees, hypocrites! for ye shut up the kingdom of heaven against men: for ye neither go in yourselves, neither suffer ye them that are entering to go in.
Luke 11:52
Woe unto you, lawyers! for ye have taken away the key of knowledge: ye entered not in yourselves, and them that were entering in ye hindered.
Christ is the key of knowledge, and men will try to keep you away from Him. If they can trick you into thinking that salvation requires work instead of simply stepping through a door, then they can manipulate you, draw you into petty competitions in the flesh, and gain power over you.
Law-oriented people cause unstable souls to stumble. When you seek the kingdom of heaven, they want you to think, “I have to do this; I failed to do that.” Instead of going through the door themselves, they try to stop you going in.