Acts 1:8 - "But ye shall receive power, after that the Holy Ghost is come upon you: and ye shall be witnesses unto me both in Jerusalem, and in all Judaea, and in Samaria, and unto the uttermost part of the earth." I'd suggest you read that text this way: "After that the Holy Ghost is come upon you, ye shall receive ability - the knowledge to witness unto me..." Growing up I attended a primary school run by Catholic missionaries; our school motto was "Knowledge is power" - and I grew up to discover that the most influential and powerful men of this world are those with a specialized kind of knowledge (Elon Musk, Bill Gates, Peter Thiel, Dangote, Einstein).
Jesus wants his disciples to be influential and powerful upon the earth in bringing many to Christ, and that is why He sent the Holy Ghost upon them - to endue them with the knowledge of the things of God. Many believers are still waiting for a "power surge" kind of experience when they talk about receiving the Holy Ghost - expecting to shake, to shout, or to fall under the anointing - but that is not what Jesus meant in Acts 1:8.
First Corinthians 2:12 tells us why God gave us the Spirit: "that we might know the things that are freely given to us of God" - the Spirit of God brings KNOWLEDGE (gnosis - insight, revelation, understanding). If the Spirit is upon you, your primary evidence should be that you KNOW God more. The "power" in Acts 1:8 is not an electric surge; it is the power to testify about Jesus accurately.
Jesus did not stop at "you shall receive power" - He gave the purpose: "...and ye shall be WITNESSES unto me." A witness in court does not need theatrics; a witness needs FACTS. You cannot witness what you do not know. That is why Jesus said in John 15:26-27, "when the Comforter is come... he shall testify of me: and ye also shall bear witness" - the Spirit testifies of Christ first in us, then we testify the same message.
Power without knowledge is just noise (Romans 10:2). Before the Holy Ghost came upon them, the apostles preached a Christ they did not fully know; afterwards, Peter stood and quoted Joel, Psalms and David (Acts 2:16-36), Stephen gave Israel's entire history from Abraham to Moses (Acts 7), and Paul reasoned with the Jews out of the scriptures for three Sabbath days (Acts 17:2-3) - that's knowledge.
The "power" was clarity, boldness and conviction that came from knowing. In conclusion: the Holy Spirit did not come upon you to make you vibrate or have a spiritual sensation - He came upon you to make you KNOW. Do not hoard knowledge - propagate! Jesus is Lord.
