We agree on a lot of things, thus we are both on FR, however the difference here is on where sins will be forgiven (plus the sense in which they are) and the purpose. In Biblical faith since effectual, obedient penitent Abrahamic-type faith is imputed for righteousness, (Rm. 4:5) rendering one "accepted in the Beloved" (Eph. 1:6) and positionalluy seated with Christ in Heaven (Eph. 1:6) by whose blood he has direct access into the holy of holies in Heaven, (Heb. 10:19) then he/she will go to henceforth be with the Lord as long as one dies in that effectual or when the Lord returns. (, (Lk. 23:43 [cf. 2Cor. 12:4; Rv. 2:7]; Phil 1:23; 2Cor. 5:8 [“we”]; 1Cor. 15:51ff'; 1Thess. 4:17) Note ) Even though as Paul who promised this direct translation, they are not actually perfect in character though he sought to be. (Philippians 3:12-21)
Thus those who sin and are forgiven during the millennial reign of Christ are the unconverted who survived the Tribulation and whom Christ shall rule over with a rod of iron (and most rebel at the end in the final test of man, when the devil is loosed for a time. (Zech. 12-14; Revelation 19:11 - 20:15) Meanwhile the redeemed with have been delivered of their vile flesh and see the Lord and receive their new bodies, which is the only transformation after this life that Paul and the NT church manifestly looked forward to, not some postmortem purgatorial process commencing at death. (Philippians 3:20-21; 1 John 3:1,2)
In contrast, under the law perfect full obedience was required, (Galatians 3:10) and which system was the epitome of salvation by merit, (Galatians 3:20) and in Catholicism one is misleadingly said to have been accounted to have truly merited everlasting life, but must actually attain perfection of character and pay any outstanding debt of suffering in order to actually enter Heaven. Which means forgiveness for "venial sins" a "redeemed" soul was perhaps ignorant of or for sins such had not yet paid the temporal penalty for.
Thus the lowest common denominator concurrence you state still leaves us with a world and an eternity of difference.