Beginning with this idea that judgement is necessary to establish justice and that in this world there is no visible justice at least not at a divine level, OT authors understood judgement to be an eschatological event. They asked God to do justice for them, to defend their cause, to save them form deceitful people (Psalms 43,1; 54,1).
But in his restraint God passed over the sins. Not that he is indifferent but he has an other plan: based on his promises, we wait for new heavens and a new earth, where righteousness dwells (2Peter 3,13). When God created humans he gave them freedom. That was already because of his grace. Remember that grace has a cost for him: giving freedom to humans was also accepting to limit himself his own freedom. This is the paradox of faith the theology had to deal with especially facing the climax of human horror during the 20th century. As says Hans Jonas the Jewish philosopher:
"After Auschwitz, we can affirm, with even greater force than ever before, that an all-powerful deity would have to be either not good [...] or totally unintelligible. But if God must be intelligible in some way and in some degree (and we must hold to this), then his goodness must be compatible with the existence of evil; and this is so only if God is not all-powerful. Only then can we maintain that he is intelligible and good, while there is still evil in the world."1
God limited his own almightiness to give some of it to humans who (as we have already mentioned) always want more. This ungrateful attitude creates an unrighteous world. But righteousness is part of the promise. And to establish righteousness, judgment is necessary to eliminate evil (Revelation 20,10 ; 21,4 ; Matthew 13,24-30 ; 36-43) but also to show that we are valuable for God and worthy of being judged: our choices matters for him because we did them with that part of freedom which he (temporarily) gave up for us!
To believe in the last judgement is to refuse to abandon the world to a logic of domination. It is also to honor God and thank him for the freedom we can enjoy through his grace. To believe in the Last Judgement is also to enter into resistance against the spirit of the world who is never satisfied by what he has. Thus it is no exaggeration to say that those who do not believe in God's judgement are partners of evil because faith in judgement is the ultimate protection against the human claim to omnipotence!
We need to fight evil, right now, in our own life (and world) with the strength that God gives through his Spirit. Fighting evil is being spiritual and pushes us to imitate Jesus’ attitude that is so clearly expressed in Philippians 2,5-8:
Adopt the same attitude as that of Christ Jesus, who,
existing in the form of God,
did not consider equality with God as something to be exploited.
Instead he emptied himself
by assuming the form of a servant,
taking on the likeness of humanity.
And when he had come as a man, he humbled himself
by becoming obedient to the point of death — even to death on a cross.
Fighting evil shows that we take judgement and justice seriously. Being committed to fight evil is what we call repentance which is linked with grace, salvation and forgiveness of sins (see Acts 2,37-40). To put it another way: "grace dies when it is fruitless"2 and if grace dies judgment and justice also. If it is so, the new earth will never be...
If we are in the fight, there is no reason to be afraid of God’s judgement as we have already noticed. 1Timothy 6,11-12 says:
you, man of God,
flee from these things,
and pursue righteousness, godliness, faith, love, endurance, and gentleness.
Fight the good fight of the faith.
Take hold of eternal life to which you were called
and about which you have made a good confession in the presence of many witnesses.
When this advice is given to Timothy, it implies that for the one that fought the good fight, eternal life is a sure outcome. So the one waiting in She’ol knows the result of judgement before it actually happens. It’s a formality. What is not a formality is to repent and to keep on fighting untill the end.