Mark 1:32 - 35 32 That evening after sunset the people brought to Jesus all the sick and demon-possessed. 33 The whole town gathered at the door, 34
and Jesus healed many who had various diseases. He also drove out many
demons, but he would not let the demons speak because they knew who he
was.
Jesus had followers, groupies, people who followed because they were curious or because they needed what Jesus offered. His disciples, at least some of them, knew who Jesus was, the Son of God, part of God Himself. His disciples and some followers knew this because of what they'd witnessed Jesus do and say.
The demons seemed to know before any of that. Jesus prevented them from speaking - "but he would not let the demons speak because they knew who he
was." This appears to be early in Jesus ministry. Recorded in the first chapter of Mark, He's preventing the demons from speaking because they knew who He was.
Why? Why prevent them from telling who He was? Perhaps a bad witness is bad witness. Perhaps someone who openly opposes God does more harm to bringing others to Christ than no witness at all? I really don't like this train of thought. I've been a bad witness, could rightly be called a hypocrite, have held grudges, refused to forgive, ignored calls to help, etc. Does this passage tell us to keep our mouths shut about who Jesus is if we aren't good witnesses?
Another thought from this passage is that Jesus has the control to not allow the demons to speak. He has the power. Jesus has the power to all things or to prevent things. Within that power is the knowledge that Jesus has of the whole story - the past, the present and the future. He knows the results of any given decision or situation. He can permit or prevent. We may never know during this life why certain things happen or don't happen. I think we have to trust that it everything is for the ultimate of God's glory. Perhaps that means what happens will bring someone to Christ who wouldn't come any other way.
Take comfort in knowing that Jesus has the power and that based on His life on earth, He obeys and is only after God's glory. So whatever we go through fits in the plan or is allowed for in the plan. And the plan is God's plan, God's good and perfect plan.