Jesus told believers in Philadelphia He is the one who opens and no one shuts, and shuts and no one opens. As we exposit this statement, we find ourselves looking at Christ's parables and see that it even ties back to Abraham.
Perception is a powerful tool. It can be used to either encourage or discourage. God has promised that He alone opens and shuts doors but the enemy will try his best to make it look like a door has closed, don't be fooled. Keep on keeping on until God moves you, you'll know when the time is.