The Christian dies in the Lord because he has been born again and given the life of Christ and so he lives his life in the Lord. The power of sin is severed in the life of the Christian. The believer will therefore die in Christ.
The unbeliever dies in his sins because he is born dead in trespasses and sins and continues to live his life in sin. The power of sin enslaves the unbeliever, making him a slave to sin. The unbeliever will therefore die in his sins.
Every person is born into this world, dead in trespasses and sins. But Christ died for the sin of the whole world, so that whosoever will BELIEVE and - that is the criteria. BELIEVE. Believe on the Lord Jesus Christ and you will be saved. Believe on Him and be saved from sin, and death and hell - saved from dying in sins. However, we have freewill and the choice to believe remains with the individual.
God in His foreknowledge knows exactly who will choose life and who will choose death. God will never force His salvation on anyone... but whosoever will trust in His only begotten Son will die in the Lord - and not perish in their sins.
The Christian has been given the most precious gift imaginable, by faith - the Life or Christ Jesus, and eternal life with Him in heaven. Just as we trusted Jesus for our Salvation (by faith) let us continue to trust Him for our Sanctification - by faith.
Thank You Father for all You did to draw me to Yourself. Thank You that I have the life of Christ, simply be believing on Jesus as my Saviour. You alone are worthy to be praised. Help me to live my life day be day in grateful thanks and praise for Your inestimable gift, in Jesus name I pray, AMEN.