Luke 24:49 (ESV): "49 And behold, I am sending the promise of my Father upon you. But stay in the city until you are clothed with power from on high."
The Holy Spirit is the promise from the Father we belong to Him. Every believer has been sealed with the Spirit of God upon belief which is the sign to heaven and earth that we belong to Him. No Holy Spirit, no salvation.
The Father gave a promise to the prophets that He would pour out the Spirit upon the people of God in a future moment (Isa 32:15; 44:3; Eze 36:26-27) because the Spirit was taken from man at the fall but would be restored through Jesus. Anyone who believes in Him will be sealed the Spirit of promise (Eph 1:13). The Spirit would also be the dowry from God to you and me that Jesus was coming back to get us!
There is a secondary experience believers have with the Holy Spirit aside from the sealing, it is called the "Epi" (upon) experience. Some call this the baptism of the Holy Spirit. It is an empowerment for ministry (Acts 1:8). All believers have the "EN" experience where the Spirit of God is inside a believer (sealing), but not upon (epi). Have you received power from on high? Pray and ask God to fill you with the power to be His witness! Amen?
Father, we thank You for the promise of the Holy Spirit. He is the power we need to live victoriously and to be a witness for You. Fill us afresh today that we might represent You well we pray in Jesus name, amen.