1. Faithfulness (not perfection), is what Christ requires to gain and maintain a saving relationship w/ Him.
(IOW): to receive Christ as Savior, a person must vow faithful (not perfect) obedience to Him as Lord (LBS). Once in that relationship (thru baptism – 1Pe 3:21), the person must (then) fulfill their former vow by living in faithful (not perfect) obedience to Christ if they hope for their saving relationship w/Him to continue.
(Exo 24:1-8 and w/1Pe 1:1-2 w/Deu 28:1-2 w/15; also Jos 23:6 w/14-16, 24:14; 1Sa 2:1-9, 12:24-25; Psa 11:7-8; Pro 3:1-4, 12:22 [notice, all that is needed to cause God to delight in us is faithfulness – not perfection]; Pro 16:6 [atonement is only offered to those who wb faithful – contra Hos 4:1]; Jer 7:22-23; Eze 18:5-9; Mat 24:45-25:46; Luk 12:42; Luk 16:10-13 [faithfulness = serving God]; Heb 10:26-30; the institution of atoning sacrifice [ability to be forgiven and remain in covenant relationship w/God] exists as one of the most obvious and powerful proofs that God has never required perfection or perfect obedience).
2. Other ways Scripture identifies faithfulness or people who have been faithfully obedient:
they are called the righteous, or practicing righteousness, are blameless, without blemish, holy, godly; they are considered those who fear the Lord, love God, are humble, are repentant, continue to bear fruit, possess a clear/good conscience (TBD).
3. That salvation requires faithfulness:
3.1. Does not negate faith in Christ (since faith in Christ that saves always includes/implies faithfulness)
3.2. Does not mean we are earning or meriting our way to heaven
3.3. Is completely reasonable given the fact that we can be faithful in our marriage to Christ
3.4. Is consistent with final judgment which is always (revealed to be) according to our deeds (Joh 5:28-29; Rom 2:6-11; 2Co 5:9-10; 1Pe 1:17; Rev 20:11-15)
3.5. Is consistent w/the warnings and possibility of apostasy which is also related to our deeds
3.6. Means that God has provided the necessary criteria by which we can accurately assess whether or not we are being (or have been) faithful to Christ.