Acts 10:34-35
34 Then Peter opened his mouth, and said, Of a truth I perceive that God is no respecter of persons:
35 But in every nation he that feareth him, and worketh righteousness, is accepted with him.
The Grace New Testament Commentary - Acts 10:35
10:35 Peter expounds God's perspective affirming that "in every nation whoever fears Him and works righteousness is accepted by Him." Peter's statement coheres perfectly with Rom 3:1-20. God looks favorably on and welcomes anyone who endeavors to do well in His sight - as Cornelius in fact did. The fact that no one can earn his or her salvation and that everyone falls short of God's glory (Rom 3:23; Isa 64:6) does not change this truth. Righteousness defines everything that corresponds to God's character and commandments whether before the Old Covenant, under the Old Covenant, or reflected in the New Covenant - regardless of whether a person has heard the actual command or not (cf. Rom 2:14).
God grants even Gentiles who fear Him and work righteousness the additional revelation that they seek and need in order to receive justification by faith (cf. Luke 13:22-30). While this in no way earns eternal salvation (cf. Isa 64:6; Rom 4:1-8; Eph 2:8-10), it does merit further revelation from God.