Atheistic logic: “If only I wasn’t an atheist, I could get away with anything. You’d just ask for forgiveness and be forgiven. It sounds much better than having to deal with guilt.” Keira Knightly
Christian response…
God the Father knows your heart (Psalm 139:2) and you will not flippantly find forgiveness of sin by mere request in your unbelief; in fact, God does not entertain the prayers of unbelievers (John 9:31) unless that prayer is one seeking obedience to the Son, Jesus Christ, as Lord (Jeremiah 29:11-13).
If you are an atheist, you are truly on your own in the cosmos and you are estranged from the Covenants of God and the promises contingent upon faith in Jesus Christ as Lord (Ephesians 2:1-10); therefore, unless the atheist is willing to humble them self, repent of their sins, acknowledge their need for forgiveness, sincerely believe in their heart and confess Jesus Christ as God who died to pay their sin-debt and believe that He was resurrected for their justification leading to Eternal life (Romans 10:9-10), the unbeliever, the atheist, the religionist, the cultist, will surely die in their sin (John 8:24) and they will die a second death in Hell (Revelation 20:11-15). Why?
Because God the Father is NOT going to permit unrepentant sin to enter His Kingdom upon death of your body in Time (Revelation 21:27). It is sin having manifest in the Kingdom of God before the creation of Time and the expulsion of the culpable parties that is the causation for all of creation that is temporarily constrained by Time/physics; therefore, God the Father is certainly not going to allow your destructive sin to defile His Kingdom (1 John 3:8b; Isaiah 14:12-14; Ezekiel 28:14-18; Luke 10:18; Revelation 12).
Atheistic flippancy and carelessness, mockery, toward the justice and holiness of God will only incite greater wrath at Judgment (Ezekiel 24:14). The facade of Atheism clearly identifies the “fool” of Time and Eternity (Psalm 14:1; Proverbs 1:7; Proverbs 9:10; Romans 1:18-32).