Every now and again, the Lord, through His word reminds us of the inevitable quality of any Christian that wants to reach heaven at last. Those who have not made it part and parcel of their lives are merely having presumptuous testimonies of being children of God and candidates of heaven.
Self-appraisal/judgment is the first and foremost thing (Matt. 7:4-5). As we appraise ourselves day-after-day, it helps us to make necessary adjustments, confess and repent of hidden sins and keep clean. Since we have judged ourselves, taken the blame, repented and made the necessary restitutions, there is no way we would be judged and condemned by the Lord as He would do to unbelievers at the end (vs 31).
Unfortunately, many people in the house of the Lord specialize in judging others instead of themselves – wives judging the husbands and vice versa, brethren judging brethren, brethren judging their leaders. But we have been warned that all such people that judge others and not themselves are blind because they did not first appraise themselves to remove their own sins (Matt. 7:3-4). They have been declared hypocrites by the Lord and all hypocrites will be cast out into outer darkness (Matt. 24:50-51). It is only the righteous and the sufficiently spiritual that can rightly assess people in the house of God or people outside (cp. Jn. 5:30; 8:15-16; 1Cor. 2:15).