Just to clarify things, from the Anti-"Calvinist" perspective on here, for the most part, and from their usual position of libel, a truncated and distorted gospel, and ignorance of facts let's talk about their usage of the term "injustice."
First, their definition and personification of injustice is summed up in Romans 9:20. So, God took care of that for all of us to see.
Secondly, which should then be obvious, they see God as unjust, "unfair" (same thing) and practicing injustice if he damns any soul to hell without giving them some chance to vote and choose themselves out of being spiritually dead (which is impossible, btw) and "into heaven." Note John 6:44; John 6:37; John 6:65; James 1:18; 2 Peter 1:1; John 6:63 &c.
Keep in mind all outside Christ are wicked, hostile toward God, deserving of hell, are owed nothing from God whatsoever. In the Anti-"Calvinist" gospel, they are owed a chance or God is seen as unjust. Yep, again, Romans 9:20 in action.
If man is owed any type of chance to do something to vote themselves in, it is no longer the Gospel of Grace, but of merit, because they've made man as one who is owed something from God. Nope. God is free, owes no person anything, and shows mercy to whom he wills; Romans 9:16; Exodus 33:17-23 and reveals himself, as well as the Son, to whom they will to do so and to none else; Matthew 11:25-30.