Many of the opponents of the Truth of Justification before God before Faith or believing, they appeal to such scriptures that indicate that one is Justified by Faith or through Faith similar to Rom 3:30
30 Seeing it is one God, which shall justify the circumcision by faith, and uncircumcision through faith.
or Rom 5:1
Therefore being justified by faith, we have peace with God through our Lord Jesus Christ:
However as those scriptures are True, those who believe are Justified by Faith, yet no matter how true that may be, it does not contradict nor deny Justification before God, based on the merits of Christ alone, before Faith or before believing. They are mere different aspects of the same Justification to be considered and believed; The Fact of the matter is this, before one can be Justified by Faith which is Justification being declared as True to us by the Gospel, Justification before God had to have existed before that declaration can be given to God given Faith.
Yes, believers are Justified by Faith Rom 5:1 since their Justification has been revealed to them and they now embrace it consciously, but their receiving it consciously is not the Act of God Justifying them before His Mind.
If a King legally acquits a prisoner on Tuesday, and the prisoner receives the good news of the acquittal that following Friday, his receiving it had no bearing on what occurred on Tuesday, he just received the good news of it in his own mind and heart later on that Friday ! Upon his receiving that good news, he becomes acquitted by Faith, he believes in or rests in the message of the good news brought to him by the Kings messenger !