The phrase "Sinners by default" means that people are considered sinners automatically from birth, without needing to actively commit a bad deed to earn that label. It implies that sin is the baseline human condition.
Theological Meaning
In Christian theology, this relates directly to the concept of Original Sin.
Inherited Condition: It suggests that humanity inherited a flawed, sinful nature from Adam and Eve.
Automatic Status: Because of this inheritance, a person does not start with a clean slate; they are born into a state of spiritual separation from God by default.
Jesus answered, “You are mistaken because you do not know the Scriptures or the power of God. (Matthew 22:29 BSB)
1 Thessalonians 4 BSB
15By the word of the Lord, we declare to you that we who are alive and remain until the coming of the Lord will by no means precede those who have fallen asleep. 16For the Lord Himself will descend from heaven with a loud command, with the voice of an archangel, and with the trumpet of God, and the dead in Christ will be the first to rise. 17After that, we who are alive and remain will be caught up together with them in the clouds to meet the Lord in the air. And so we will always be with the Lord.
1 Corinthians 6 BSB
9Do you not know that the wicked will not inherit the kingdom of God? Do not be deceived: Neither the sexually immoral, nor idolaters, nor adulterers, nor men who submit to or perform homosexual acts, 10nor thieves, nor the greedy, nor drunkards, nor verbal abusers, nor swindlers, will inherit the kingdom of God. 11And that is what some of you were. But you were washed, you were sanctified, you were justified, in the name of the Lord Jesus Christ and by the Spirit of our God.
Note that we are declared righteous from the outset:
Romans 5:1-11 NET
1Therefore, since we have been declared righteous by faith, we have peace with God through our Lord Jesus Christ, 2through whom we have also obtained access by faith into this grace in which we stand, and we rejoice in the hope of God’s glory.
9Much more then, because we have now been declared righteous by his blood, we will be saved through him from God’s wrath. 10For if while we were enemies we were reconciled to God through the death of his Son, how much more, since we have been reconciled, will we be saved by his life?