Chosen by God to Receive Mercy

How can God be just and only choose to save some sinners from Hell when he has the power to save all sinners from Hell? Mankind is to blame for being worthy of Hell and God is just in sending us there. But God's Mercy is his to dispense with as he wishes. No one can make a claim on him that they deserve his mercy. God can have mercy on the elect because Christ has satisfied God's just penalty for sin and requirement for obedience for them. Jesus came to save specific sinners chosen by God who he knew by name. Thus, none of Christ's blood was shed in vain but Jesus has succeeded in saving all who he came to save. This doctrine has great importance for the comfort of a Christian and for our witness to the world around us.