Remission of sins is Justification !
Remission of sins is an aspect of Justification, and can even be called Justification, as it pertains to being justified from all the legal consequences of our sins, for this is what Paul means by it here Acts 13:39
And by him all that believe are justified from all things, from which ye could not be justified by the law of Moses.
Some Translations have the right Ideal here:
39 And that through Him everyone who believes [who acknowledges Jesus as his Savior and devotes himself to Him] is absolved (cleared and freed) from every charge from which he could not be justified and freed by the Law of Moses and given right standing with God.AMP
and in Him every believer is absolved from all offences, from which you could not be absolved under the Law of Moses.WNT
To absolve means:
to free from guilt or blame or their consequences: The court absolved her of guilt in his death.
2.
to set free or release, as from some duty, obligation, or responsibility (usually followed by from ): to be absolved from one's oath.
3.
to grant pardon for.
4.
Ecclesiastical .
a.
to grant or pronounce remission of sins to.
b.
to remit (a sin) by absolution.
c.
to declare (censure, as excommunication) removed.
Being Justified from all things as Per Acts 13:39 means being Justified from all the consequences of ones sins, and it means things the law of Moses in it's Leviticus priesthood with its animal sacrifices could not do ! See Heb Chp 7-10 ; And this Justification of remission of sins is solely accomplished on the death/ blood of Christ Matt 26:28
28 For this is my blood of the new testament, which is shed for many for the remission of sins.
Heb 9:22
22 And almost all things are by the law purged with blood; and without shedding of blood is no remission.
Eph 1:7
7 In whom we have redemption through his blood, the forgiveness of sins, according to the riches of his grace;
Now that Justification here in Acts 13:39 pertains to the forgiveness of sins is seen from what is said in Vs 38
38 Be it known unto you therefore, men and brethren, that through this man is preached unto you the forgiveness of sins:
Forgiveness of sins is the negative side of Justification, but does have a positive effect, it gives the forgiven reconciliation to God even while they are enemies Rom 5:10
10 For if, when we were enemies, we were reconciled to God by the death of his Son, much more, being reconciled, we shall be saved by his life.
Reconciliation is because of forgiveness, which is Justification ! This Truth also confirms Justification before Faith !