To forgive someone presupposes that someone has offended you, or, that you have taken offence for some reason.
Question: Can you forgive that one even if they refuse to accept your forgiveness – seeing as "forgiveness" is in your power to give. So, if you deem someone to be "forgiven!" are they indeed forgiven; is forgiveness affected towards them regardless of their personal response to it? i.e., whether they accept it or not.
If one answers "No they are not forgiven" – then this needs explaining as to how it is that they are not forgiven.
If one answers "Yes they are forgiven" – then how is it that God cannot have ministered the selfsame forgiveness through Jesus Christ toward humanity? Does humanity's "apparent" refusal, be it in ignorance or arrogance, nullify the work of the Cross in drawing "all" to Himself? [Jn 12:32]. What did Paul say:
"For what if some did not believe? Will their unbelief make the faithfulness of God without effect? Certainly not!" Rom 3:3-4a.
What did God say through His prophet Isaiah concerning Israel's state of wanton rebellion?
Isa 44:22 I have blotted out, like a thick cloud, your transgressions, and like a cloud, your sins. Return to Me, for I have redeemed you.”
"Return" [an act of repentance] is only possible because of the prior establishment of redemption – not unlike that of Rom 5:10 "when we were enemies we were reconciled".
It may be argued that one must believe to benefit from it – true on one level, but does that mean that un-forgiveness, therefore, remains – no! It simply means that life is not being lived to the full in experiencing the benefits of forgiveness.
Now believing is an important matter, but believing does not determine where one ends up when this life is over – if OUR believing could establish that, then what need was there for the Cross? – was THAT even the focus of what "believing" was all about?
Believing truth does not make truth true, belief does not create truth – truth, however, can create belief. You cannot invent something to believe and make it truth, no; you must discover truth and then agree with it – accepting it and so making it applicable in your life.
For instance: You do not have to believe in gravity for gravity to have its total effect on you, as much as someone else who does believe in and understands gravity – belief or non-belief does not negate the effect of gravity upon you. So, what does "believing" in gravity do for you? It will save you – you will not do what you know to be contrary to gravity and thus endanger your life. Through experience-observance, you conclude that gravity is an absolute – regardless of belief. Believing in gravity, however, makes it beneficial – rather than struggling against it. So, whether we believe it or not, absolute truth affects us – however, it can benefit us greatly if we accept it, just as it is.
Another example: The person who is kidnapped does not have to believe a ransom has been paid; the police however do. Once the ransom is paid the police move in to free the person. Likewise, it was God that had to believe the ransom had been paid – in full. Once the ransom was paid [1Tim 2:5-6; 1Jn 2:2] and He satisfied that it was [Isa 53:11], deliverance came to all. That is why "redemption-reconciliation" was solely an issue between God and Christ alone – but always on humanity's behalf. Believing this is where "salvation" becomes an issue for the individual.
It is a clear biblical doctrine and teaching that one person can determine the destiny of the entire world. It's just that evangelicalism believes that the first Adam had the power to do that, but the last Adam did not. The last Adam did not die to give this world a chance to live in the presence of God when this life was over. No, Jesus Christ died to redeem and reconcile the entire world back to God completely – and the benefits of that start in this life in the here-and-now. The result: if you will but believe it, you will be able to experience in this life now some of what is coming in the next. It was this that Jesus determined and established in the Cross-Parousia event near 20 centuries ago.
This is what LIFE is all about – we have been forgiven-redeemed-reconciled, now come walk in it; doing so brings rest [salvation-transformation] to the soul [the inner man].
Think about it – how is it that God would require and demand of believers, something that He himself cannot or will not do – to love and forgive one's enemies – the very thing the likes of 'eternal conscious torment' and 'annihilationism' implicitly denies God does.
With absolutely no repentant faith response from those involved in his crucifixion, Jesus prayed to God – "Father, forgive them; for they know not what they do" [Lk 23:34].
Questions to ponder:
 Who really nailed Jesus to the cross?
 Did God really answer Jesus' prayer?
 What are the implications of your answers?
Forgiveness lies in the heart of the forgiver [God] – so much the better when we the forgiven realise it.