In Luke 10: 17-20, the seventy return with joy, saying, “Lord, even the demons are subject to us in Your Name.”
Jesus replies, “Nevertheless, do not rejoice in this, that the spirits are subject to you, but rather, rejoice because your names are written in heaven.”
Why are they not to rejoice in their authority over demons in Jesus’ name?
People rejoice over having received some great and unexpected blessing. Having authority over demons is not in that category. Of course they (and we) have authority over demons in Jesus’ name. He has that authority as their creator and has agreed to let us use it as His servants.
It’s the same as a trusted employee using his employer’s credit card. Being able to buy something with it wouldn’t be an unexpected blessing. But if the employer gave him a huge mansion and promised a life of unheard of luxury, that would be something to rejoice over.
The great and unexpected blessing is that he’s given us the right to dwell in Heaven with Him forever and nobody can take that away from us. Now that’s cause for rejoicing.