Galatians 3:14…in order that in Christ Jesus the blessing of Abraham might come to the Gentiles, so that we might receive the promised Spirit through faith.
No matter how long you live here on earth, you can never plumb the depths of all this promise entails. Never.
The promise from God is given freely, not through law-keeping but through faith. It is part of an inheritance, received only by those to whom it is promised. We receive by faith, not by impressing, not by earning, and definitely not by merely looking the part (i.e. going to church services and keeping up with the ‘spiritual’ Joneses).
The promised Spirit. To understand Who the “promised” Spirit may be, or what is included in this “promise” we must read through some prophecies that faithful Israelites were looking to God to fulfill. Isaiah taught that God would pour out His Spirit, changing the wilderness into a fertile field (Isaiah 32:15ff). Also that the pouring out His Spirit would make the faithful like poplars or willows along the banks of an ever freshly flowing river (Isaiah 44:1-5). When Christ came, and ushered in His Kingdom, these promises, and the realities of eternal life (the Law was only a shadow, a tutor), He taught about the rivers of water that would flow through us (see John 7:37-39, re-read it, breath deeply, read it again).
The Promised Spirit assures us that we are His (1 John 4:13), teaches us, comforts us, leads us into His revealed truth and away from falsehood and false ways of seeing the world and ungodly reactions to the world. The promise of the Spirit is the promise that we would become more and more like Christ as He works in our hearts (see Galatians 5). The promised Spirit is the guarantee of heaven, of living in the land where righteousness dwells and enjoying all the blessings of heaven. The intimacy the Spirit cultivates in us fits us for heaven, and for enjoying the glory of God in its fullness.
As promised, He keeps my heart from living in despair, He really does renew my inner man, day by day, especially in the midst of troubles and hardships (or, tribulations as Jesus said we would now experience). When downcast, He has refreshed me, revived me, taken Jesus’ words and made them so precious to me. There are moments when I foolishly want to abide in my downcast mood, and fret about circumstances. But He lifts our heads, He brings our gaze back to the cross, and to the heavenly places where Christ is now seated.
His promised Spirit gives wisdom and understanding as we walk further with Him, abiding in Him–revealing to us all that has been given to us in Christ (see 1 Corinthians 2!). The promise of the Spirit is also unity, with all those truly united to Christ. On His cross Jesus broke down all the barriers to our unity, and now through the work of His Spirit we can enjoy this–but on His terms, not ours. The unity of the Spirit, His bond of love, perfect love that does not violate His Word.
Where the Spirit of the Lord is, there is freedom [from sin, death, the law’s condemnation; cf John 8:34]. But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory, just as from the Lord, the Spirit. 2 Corinthians 3:17-18