Rom 4:5 But to him that worketh not, but believeth on him that justifieth the ungodly, his faith is counted for righteousness.
It is because his faith is counted for righteousness.
It is because Abraham "believeth on him".
IOW believing the same thing God believes
or belief in accordance with God
. So, this belief
that we call biblical "faith" that "is counted for righteousness" because it denotes what We believe in accord with God.
And what makes a believer 'righteous' is that all belief in reality and faith originates in and with God. Belief and faith didn't start in and with man, but belief and faith originated in and with God. And disbelieving it didn't has implications, one being that anyone disbelieving God believes won't be able to understand or interpret what the Bible means in reality. The Bible speaks more of belief than any other subject not because God doesn't believe or Christ didn't have faith, but it speaks more of belief and faith because Christ had faith and God believes. And if one disbelieves 'God believes', then that same one can't be a believer, because all believers believe their faith and belief originates in and with God.
And now apart from law hath the righteousness of God been manifested, testified to by the law and the prophets, and the righteousness of God [is] through the faith of Jesus Christ to all, and upon all those believing, -- for there is no difference, for all did sin, and are come short of the glory of God -- being declared righteous freely by His grace through the redemption that [is] in Christ Jesus, whom God did set forth a mercy seat, through the faith in his blood, for the shewing forth of His righteousness, because of the passing over of the bygone sins in the forbearance of God -- for the shewing forth of His righteousness in the present time, for His being righteous, and declaring him righteous who [is] of the faith of Jesus
. Where then [is] the boasting? it was excluded; by what law? of works? no, but by a law of faith: therefore do we reckon a man to be declared righteous by faith, apart from works of law. (Romans 3:21-28)
What, then, shall we say Abraham our father, to have found, according to flesh? for if Abraham by works was declared righteous, he hath to boast -- but not before god; for what doth the writing say? `And Abraham did believe God, and it was reckoned to him -- to righteousness;' and to him who is working, the reward is not reckoned of grace, but of debt; and to him who is not working, and is believing upon Him who is declaring righteous the impious, his faith is reckoned -- to righteousness: even as David also doth speak of the happiness of the man to whom God doth reckon righteousness apart from works: `Happy they whose lawless acts were forgiven, and whose sins were covered; happy the man to whom the Lord may not reckon sin.' (Romans 4:1-8)
And having the same spirit of the faith, according to that which hath been written, `I believed, therefore I did speak;' we also do believe, therefore also do we speak; knowing that He who did raise up the Lord Jesus, us also through Jesus shall raise up, and shall present with you, for the all things [are] because of you, that the grace having been multiplied, because of the thanksgiving of the more, may abound to the glory of God; wherefore, we faint not, but if also our outward man doth decay, yet the inward is renewed day by day; for the momentary light matter of our tribulation, more and more exceedingly an age-during weight of glory doth work out for us -- we not looking to the things seen, but to the things not seen; for the things seen [are] temporary, but the things not seen [are] age-during. (2 Corinthians 4:13-18)
But when I saw that they are not walking uprightly to the truth of the good news, I said to Peter before all, `If thou, being a Jew, in the manner of the nations dost live, and not in the manner of the Jews, how the nations dost thou compel to Judaize? we by nature Jews, and not sinners of the nations, having known also that a man is not declared righteous by works of law, if not through the faith of Jesus Christ, also we in Christ Jesus did believe, that we might be declared righteous by the faith of Christ, and not by works of law, wherefore declared righteous by works of law shall be no flesh.' (Galatians 2:14-16)
Why, then, the law? on account of the transgressions it was added, till the seed might come to which the promise hath been made, having been set in order through messengers in the hand of a mediator -- and the mediator is not of one, and God is one -- the law, then, [is] against the promises of God? -- let it not be! for if a law was given that was able to make alive, truly by law there would have been the righteousness, but the Writing did shut up the whole under sin, that the promise by faith of Jesus Christ may be given to those believing. (Galatians 3:19-22)
Wherefore having girded up the loins of your mind, being sober, hope perfectly upon the grace that is being brought to you in the revelation of Jesus Christ, as obedient children, not fashioning yourselves to the former desires in your ignorance, but according as He who did call you [is] holy, ye also, become holy in all behaviour, because it hath been written, `Become ye holy, because I am holy;' and if on the Father ye do call, who without acceptance of persons is judging according to the work of each, in fear the time of your sojourn pass ye, having known that, not with corruptible things -- silver or gold -- were ye redeemed from your foolish behaviour delivered by fathers, but with precious blood, as of a lamb unblemished and unspotted -- Christ's -- foreknown, indeed, before the foundation of who through him do believe in God, who did raise out of the dead, and glory to him did give, so that your faith and hope may be in God. (1 Peter 1:13-21)