Justified before believing and why ?2
The First reason for Justification before God before believing has been given, because of non imputation of sin.
Now the Second Reason is because of Imputation of Christ's Righteousness. Rom 4:6-7
6 Even as David also describeth the blessedness of the man, unto whom God imputeth righteousness without works,
7 Saying, Blessed are they whose iniquities are forgiven, and whose sins are covered.
All for whom Christ died, by His Death for them alone, it makes them [before God] Righteous.
This is seen the Prophecy of Isa 53:11
11 He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities.
AMP 11 He shall see [the fruit] of the travail of His soul and be satisfied; by His knowledge of Himself [which He possesses and imparts to others] shall My [uncompromisingly] righteous One, My Servant, justify many and make many righteous (upright and in right standing with God), for He shall bear their iniquities and their guilt [with the consequences, says the Lord].
ESV Out of the anguish of his soul he shall see and be satisfied;
by his knowledge shall the righteous one, my servant,
make many to be accounted righteous,
and he shall bear their iniquities.
Rom 5:19
19 For as by one man's disobedience many were made sinners, so by the obedience of one shall many be made righteous.
AMP 19 For just as by one man’s disobedience (failing to hear, heedlessness, and carelessness) the many were constituted sinners, so by one Man’s obedience the many will be constituted righteous (made acceptable to God, brought into right standing with Him).
That's Justification. All this was accounted before they believed, had nothing to do with their personal belief, in fact, it was true while they were enemies, and it is the reason why they do believe after God reveals it to them by the Gospel of their Salvation, they are then persuaded of its fact or reality.