1. A man is justified by believing in Jesus as the Christ. (Gal 2:16)
    1 Jn 5:1, Rom 1:17, Hab 2:4, Gal 3:2, Acts 5:32, Rom 3:23-26, 28,
    Rom 4:5, Rom 5:1, Eph 2:8, Phil 3:9

The Old Testament prophesied that the righteous would live by faith. (Hab 2:4)

Hab 2:4 Behold, his soul which is lifted up is not upright in him: but the just shall live by his faith.

Righteousness from God can be obtained through faith in Jesus Christ, from beginning to end. (Rom 1:17, 1 Jn 5:1, Rom 3:23-26,28, Rom 4:5, Phil 3:9)

Rom 1:17 For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith.

1 Jn 5:1 Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth him that begat loveth him also that is begotten of him.

Rom 3:23 For all have sinned, and come short of the glory of God;
24 Being justified freely by his grace through the redemption that is in Christ Jesus:
25 Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
26 To declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus.
28 Therefore we conclude that a man is justified by faith without the deeds of the law.

Rom 4:5 But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness.

Phil 3:9 And be found in him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith:

By the grace of God, we have come to believe that Jesus is the Christ. (Eph 2:8)

Eph 2:8 For by grace are ye saved through faith; and that not of yourselves: it is the gift of God:

Receiving the Holy Spirit is not by works of the law, but through faith in Jesus as the Christ. (Gal 3:2, Acts 5:30-32)

Gal 3:2 This only would I learn of you, Received ye the Spirit by the works of the law, or by the hearing of faith?

Acts 5:30 The God of our fathers raised up Jesus, whom ye slew and hanged on a tree.
31 Him hath God exalted with his right hand to be a Prince and a Saviour, for to give repentance to Israel, and forgiveness of sins.
32 And we are his witnesses of these things; and so is also the Holy Ghost, whom God hath given to them that obey him.