From the perspective of one in eternity, this may be the case, but I don't believe people can reason properly when God's perspective (which we can't have) is a part of their logic. We can basically repeat what God told us about what He sees in eternity.
From a human perspective (cause and effect), Jesus does not need to die again when someone repents. His death paid for everyone's sins, but people that do not come under His authority do not receive the benefit of it. That is, He is everyone's Savior, but not everyone benefits (1 Timothy 4:10).
1. We can't be forgiven unless we believe He is real (otherwise we would actually be repenting to an imagined figure).
2. We won't be forgiven unless we want to be forgiven (forgiveness then being contrary to our will/request).
3. We won't be forgiven unless we believe He has the authority to forgiven (though the grocery store clerk is real, he/she is not God).
4. One wouldn't be forgiven without accepting God as "my" God. If He is God but not my God, I have not accepted the truth about His authority over me (a part of which is the authority to forgive). If one is not willing to obey God, then one is trying to get something from a false God. The real God is the Lord of all.