The Spirit still has an active role even today. Even though the Spirit "inspired" the word of God, his ministry did not end with the word. Even though the Spirit enabled the early disciples to speak boldly in the name of Christ, his ministry was not limited to them. Even though the Spirit gave various miraculous gifts, his ministry did not end when he stopped giving those gifts as he once did.
Peter said that we would receive the Spirit when we repent and are baptized. "For the promise is for you and your children and for all who are far off, as many as the Lord our God will call to Himself" (Acts 2:39).
What does the Spirit do even today? One of the things the Spirit does is acts as a pledge or guarantee.
"In Him, you also, after listening to the message of truth, the gospel of your salvation--having also believed, you were sealed in Him with the Holy Spirit of promise, who is given as a pledge of our inheritance, with a view to the redemption of God's own possession, to the praise of His glory" (Eph 1:13-14).
Spirit is a "pledge" of our inheritance. In other words, receiving of the Spirit is only a down payment on what is still to come. So, what is it that is still to come? It is our redemption. It is a new body. It is new life.
"But if the Spirit of Him who raised Jesus from the dead dwells in you, He who raised Christ Jesus from the dead will also give life to your mortal bodies through His Spirit who dwells in you" (Rom 8:11).
God has granted us eternal life. It is guaranteed, and the guarantee is the Spirit whom he has given us.
Related to this idea is our sonship. Yes, The Spirit is involved in identifying us as children of God. The Spirit gives us a new identity. It "re-characterizes" us as children of God
"For all who are being led by the Spirit of God, these are sons of God (Rom 8:14).
"The Spirit Himself testifies with our spirit that we are children of God (Rom 8:16).
"Because you are sons, God has sent forth the Spirit of His Son into our hearts, crying, "Abba! Father!" (Gal 4:6).
Another way to talk about this re-characterization is sanctification. We have been sanctified, which means that we have been set apart, or "re-characterized." We are different. We are dedicated and devoted to God and his purposes. We belong to him now. The Spirit sanctifies us as children of God, which means we are no longer children of this world, but aliens.
"Peter, an apostle of Jesus Christ, To those who reside as aliens, scattered throughout Pontus, Galatia, Cappadocia, Asia, and Bithynia, who are chosen according to the foreknowledge of God the Father, by the sanctifying work of the Spirit, to obey Jesus Christ and be sprinkled with His blood: May grace and peace be yours in the fullest measure" (1 Pet 1:1-2).