Power in the new testament is mainly exorcia (not sure of spelling) or dunamis. Exorcia=authority (which we have in the name of jesus) and dunamis=
doo'-nam-is
force (literally or figuratively); specifically miraculous power (usually by implication a miracle itself): - ability, abundance, meaning, might (-ily, -y, -y deed), (worker of) miracle (-s), power, strength, violence, mighty (wonderful) work.
Often we hear quoted "you shall receive power when the holy ghost comes upon you".
It is often this kind of poor hermeneutics that lead me to error when i was a pentecostal extremist (Still pentecostal but as instructed by scripture) so lets examine the whole verse and not just the sentence.
Acts 1:8 (New International Version)
8 But you will receive power when the Holy Spirit comes on you; and you will be my witnesses in Jerusalem, and in all Judea and Samaria, and to the ends of the earth."
1. Dunamis is promised when the holy Spirit comes on us.
2. We will all experience dunamis when truelly baptised with the Holy Spirit.
3. dunamis is defined as miracle power and every single beliver that is baptised by the holy spirit is a partaker of such power.
2 Peter 1:3-4 (New International Version)
3 His divine power(dunamis) has given us everything we need for life(eternal life) and godliness through our *knowledge* of him who called us by his own glory and goodness. 4 Through these he has given us his very great and precious promises, so that through them you may participate in the divine nature and escape the corruption in the world caused by evil desires.
but.....
4. Reading Acts 1:8 we notice the structure is two fold first power is received when the Holy Spirit comes on us (This we must understand is a new covenant promise) the second part Jesus tells us what this power is for. Simply to witness the gospel to all ends of the worlds.
5. It is a greater miracle for a dead spirit to come alive through Christ than for a dead body to be resurrected. So when we witness and a soul is saved its a greater miracle than laying hands on a dead body. The greatest miracle is salvation not any other sign or wonder as great as they are.(Are signs and wonders for belivers or unbelivers? If i need a sign or wonder what does this say about my faith?)
6. dunamis is expressed in many ways other that physical healing, by his stripes the bible tells us we are healed form the inherent condition of sin, walking in the Spirit gives us the dunamis to overcome the flesh.
7. Preaching or proclaiming the gospel with boldness was always preceded by the apostles being filled with the Holy spirit and then the dunamis to proclaim would always follow.
8. The dunamis to love as Christ loves us does not come from us but from he that dwells in us.
9. working of miracles is a gift of the Spirit (but this doesn't mean we cant pray for miracles when needed) just like all other gifts powered by the dunamis of the Holy Spirit these gifts are given to whoever the spirit wills
1 Corinthians 12:29 (New International Version)
29 Are all apostles? Are all prophets? Are all teachers? Do all work miracles?
Obviously not.
Conclusion
Salvation is the greatest miracle. God so loved us that he was willing to die on cross for our salvation. Demons can work just almost every miracle but salvation if im looking for his power its not where signs and wonders are manifested the most its where people have met christ and the power to change them form a wretched sinner to a new man who is a partaker of the divine nature is present.
Testimony
My wife dragged me to a church a few months back. The man of God had a strong prophetic gift he could call out entire families and tell them really distinct things people would cry fall over , be slain (all the normal excess) and it was a really overwhelming experience. well.. i figured since the bible says we should covet the best gifts i said to myself why not. So i prayed and asked God in "Faith" for the same sort of Gift....
The Spirit showed me what was really going on and he said a funny word i have never heard. He didnt let me sleep that night and so i woke up at 3am turned on my laptop to look up the funny word the Spirit had told be about. lo and behold it was the name of a demon associated with mysticism so you can guess i withdrew my request for the "man of God" gift and never went back. I have learn in my short journey like paul says love must always precede gifts otherwise error is inevitable.
God Bless