Many people who sin frequently in the sight of others, and then confess in secret to God, have been forgiven by Him and, being well-pleasing to Him, have received the Holy Spirit. Those whom we reckon to be sinners (of whose repentance we are unaware) are justified in the sight of God. This is because we see the sins which they have committed, yet we know nothing of the good deeds which they have performed in secret. Hence, we should not condemn anyone, even if we perceive him sinning with our very eyes. For as soon as the sinner has taken ten steps away from us, we are not in a position to know what he has done in secret or what God has done for him.
For example towards the evening of Great Thursday, Judas the betrayer was with Christ and the Disciples, whereas the thief was in the company of criminals and murderers. But when Friday came, Judas betrayed the Lord, whereas the thief, because he repented on the Cross, went to dwell in Paradise with Christ.
Let us keep in mind the words of the Lord “Judge not, and you shall not be judged. Condemn not, and you shall not be condemned.” (St. Luke 6:37).
In other words if we do not judge others, the Lord will be merciful to us on the day of Judgement, but, if we judge others then He will judge us strictly.