By Paulist Protestant Doctrine, Sinners are unconditionally allowed into Heaven. This is the primary reason why I suppose that Paul was the Antichrist.
Christ had taught that Souls would be Judged. Christ mentions a few times that there would be separate ranks, different Mansions in Heaven.
Christ was killed before he could teach everything, and much of what we know comes from the Saints.
The Propensity to Sin is dealt with in Purgatory. Purgatory is not a function of justice, of retribution. Purgatory is intended to make Accepted Souls fit and acceptable for admittance into the Higher Inner Circles of Heaven.
It is said that Purgatory was evolved almost by accident. Heaven had been divided between the Purely Righteous and those who still had the contamination of Sinfulness, and those who were stained were kept out of the Main Holy City. Well, Light poured from the Holy City, and this light burned like a fire on those Souls that were opaque with impurities. It was thought that Souls would flinch from the Pain and escape from it. But these Souls stood they ground and tolerated the Pain until the Sins and the Sinfulness were burned out of them, until they were burned clean.
Of course, these souls were reevaluated and found, surprisingly, pure enough to enter into the Holy City. Purgatory was soon enough formalized, institutionalized and systematized. Souls would start low and would gradually be raised to more and more intense levels of the Purifying Light. A tradeoff was made between Time Applied and the Levels of Pain endured.
What source (ie authority) does this come from - St Augustine? Plato? Dante?