First, since God is eternal, the event of Christ taking on my sins and my receptive of his redemption is a single event in his mind. Consequently, my individual faith that receives the remission of sins and the event that works the remission are identical. Faith means being incorporated into Christ's already existent event of forgiveness. That's why the NT always talks about "abiding in Christ" (John) or "being in Christ Jesus" (Paul). Or as to becoming a single subject with Christ- as Luther describes it in his "happy exchange" language.
Secondly, this shows part of the problem that our opponents have with universal objective justification. Since they conceptualize individual salvation and atonement as two separate events, they assume that atonement can't=forgiveness/justification. They assume that a universal justification necessarily contradicts individual justification through faith. They assume this works two ways. 1. That a universal justification makes individual justification unnecessary or repetitive. So the argument goes, if Abraham was already justified by faith, wouldn't he be justified again by the death of Christ? 2. That a universal justification contradicts an individual justification through faith.
The only solution, they assume, is to say that there's something called atonement which isn't forgiveness (though what it is they can't seem to explain), then a justification by faith.
But that's only if you assume that these are different events. If you assume that justification means "abiding" in Christ as a single subject via the "happy exchange," then there's no problem with asserting universal justification and justification by faith. They form a single event.
Of course, they remain temporally different in sequence, but in the mind of God they are one event of me receiving all that is Christ and Christ taking on my sins.
Justification means that I enter into Christ's objective reality of forgiveness. It is to "abide" in him.