Lets say that you are the heavenly father of your home and that you fathered 5 children. And, that you have the sovereign power to select which child would be saved and which child would be condemned. Which one of your children would you choose to be saved and which one of your children would you choose to be condemned? What would be your bases for your choice for the ones that you chose for salvation and the others for condemnation? How would the love that you have for the ones you chose for salvation differ from the ones that you chose for condemnation? Its hard to imagine, right. Of course it is, because this is also biblically unimaginable. Eph 2:8,9 say, for by grace you are saved through faith, and this is not from yourselves, it is the gift of God; it is not from works, so that no one can boast Now the pronoun 'this and it' which is the gift of God is not faith, but is the saving grace. The faith is active and it is yours. Therefore, God did not have to choose which child would be saved or condemned because he chose to save us all through the saving work of Jesus Christ on the cross so that all who believe in Him will not perish but have eternal life (John 3:16), God's sovereignty points to the salvific grace and man's responsibility points to his faith that he has in that saving grace.
Think about it. In Numbers 21:4-9 which of the wilderness travelers did God choose to make look at the serpent on the stick and live, and which of them did He choose to make not look at the serpent and die? John 3:14-15 say, Just as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, so that everyone who believes in him may have eternal life.