Matthew 10:1 says, “Jesus summoned His twelve disciples and gave them authority over unclean spirits, to cast them out, and to heal every kind of disease and every kind of sickness.”
As Christians, we get the same authority.
But the reason why we don’t see many miracles today, is because:
No intimacy with the Lord
We don’t spend enough time in the presence of God, praying and communing with Him. Spiritual power and authority are birthed in intimacy with the King.
We do not live holy lives
1 Peter 1: 16 says, “Be holy, because I am holy”. But many people get “saved” in seeker sensitive churches where all talk of sin and repentance is absent, so they think they are saved but are not. In addition, they are living their lives as they see fit, with no one to tell them they are living in sin, so they do whatever they want, with the “added” benefit of Jesus (who they think they know but do not).
We have no power when we do not live holy lives, forsaking the things of this world, so then Satan has power over us instead of us having power over him.
3. We do not believe.
Having said all this, when people claim to be Christians, are able to perform miracles, but do not meet the above “criteria”, they are drawing on occultic powers, so miracles are done, but not in the name of Jesus.
An example in this case, is Bethel Church, who do not preach the gospel, but teach their members to perform miracles. For more info, refer to this warning.
For more info about spiritual power, check out this blog post: https://resetexchange.com/how-christians-block-gods-magic/