Secondly, the simple fact is that men were, and still are...justified by grace through faith alone.
The one thing you need to know in regards to justification is that you cannot, listen now, cannot equate justification as obtained by Abraham and the Old Testament Saints with Eternal redemption.
Sure, Abraham was justified by grace through faith, and his faith was credited as righteousness. However, Abraham died still in need of his sins being redeemed through the Blood of Christ:
Hebrews 9:12-15
King James Version (KJV)
12 Neither by the blood of goats and calves, but by his own blood he entered in once into the holy place, having obtained eternal redemption for us.
13 For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh:
14 How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?
15 And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance.
Our Eternal Redemption, as well as that of the Old Testament Saints who were justified by grace through faith alone...was obtained for us by Christ dying on the Cross. "His Blood" is His Death. The sacrifices Abraham offered up sanctified to the cleansing of the flesh, or in other words, it was physical, not spiritual, not eternal. His death redeemed the transgressions which were under the Law.
To illustrate the difference, I can say I am justified in saying you have embraced false religion and in no way can be considered a Baptist. And that has nothing to do with my, or your...eternal destiny. The only thing that eternal destiny rests on is our response to the Ministry of the Comforter when He brings conviction of sin, righteousness, and judgment. He will do this by enlightening the natural mind to the truth of the Gospel.
And right now you are a Christ rejecting religionist.
Paul speaks of this same retroactive redemption here:
Romans 3:20-26
King James Version (KJV)
20 Therefore by the deeds of the law there shall no flesh be justified in his sight: for by the law is the knowledge of sin.
21 But now the righteousness of God without the law is manifested, being witnessed by the law and the prophets;
22 Even the righteousness of God which is by faith of Jesus Christ unto all and upon all them that believe: for there is no difference:
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.
Understand?
Abraham was justified by grace through faith alone, but he was also justified by works according to James. Contradiction? No...
...because in view is not eternal redemption which is bestowed freely as a gift by God.
We are justified freely by His grace through the Redemption which is in Christ Jesus. His Death brings remission for sins that are past. His Blood redeems the transgressions which were under the Law.
Christ is the One that starts, and finishes...our salvation:
Hebrews 12:2
King James Version (KJV)
2 Looking unto Jesus the author and finisher of our faith; who for the joy that was set before him endured the cross, despising the shame, and is set down at the right hand of the throne of God.
Trust Christ. Not yourself.
Philippians 1:6
King James Version (KJV)
6 Being confident of this very thing, that he which hath begun a good work in you will perform it until the day of Jesus Christ:
God bless.