Paradise before the atonement

Before the atonement Paradise was a place of comfort for the righteous deceased, a place angels could access, but not Heaven. It was a part of “sheol”, the place dead people reside, but not uncomfortable or inhospitable.

Jesus' description of Paradise in Lk 16.19-31 rules out it being in Heaven because this Paradise provided visibility and person-to-person communication between people in comfort and people in torment.  Our understanding of Heaven is that such visibility and communication is not available or possible.

An example of a believer, one of the people God chose to save, e.g. one of the “elect”, who was residing in a place “down” from earth, e.g. where Sheol was envisioned, rather than “up” from earth, where heaven is envisioned, was Samuel. When King Saul employed a medium to summon the deceased Samuel, she saw him as coming “up” to them. Samuel had the same perspective, as indicated by his question to Saul, “Why have you disturbed me by bringing me up?” Ref. 1 Sam 28.15.

In Rom 3.25 Paul wrote that prior to the atonement God had left the sins committed before the atonement (temporarily) unpunished.  Thus, it is possible God used Paradise prior to the atonement as a place of temporary comfortable residence for the saints who died in faith prior to the atonement -- awaiting the time when their sins would be fully atoned for by Jesus' substitutionary death.

After Jesus had completed His atoning work, when He cried "Tetelestai!", "It is finished!", all the saints' sins for all time had been atoned for.  From then on Paradise was probably just another name for Heaven.  An indication of that was Paul's vision, which occurred after the atonement, where he looked into Heaven, which he also referred to as Paradise (2 Cor 12.2-4).