A doctrine often overlooked is the doctrine of the faith of Jesus Christ. The faith of Christ that justifies the believer was not available until after the resurrection. Before the resurrection man was justified by his own individual faith which required obedience, faith requires evidence. Even then, man's justification could only lead to self righteousness under the law which could never take away sin, but could keep the faithful servant from condemnation in Abraham's bosom upon death.
The faith of Jesus Christ is God's righteousness without the law available to those who trust in the gospel of Jesus Christ. Abraham is a type of believer in the OT but is not identical to the NT believer. Paul uses him in type to explain what we have available now. Abraham did not have God's righteousness through the faith of Christ.