James 4:11-12

Judging proceeds talking negatively about someone.

How we judge others says a lot about us. Need to look into the soul to judge fairly. When we're motivated by jealousy and pride we will never be able to judge perfectly. Pride is competitive by nature (Luke 18:9-14). By desiring to lift yourself up you'll be prone to compare in a sinful manner. Becoming a disciple of Jesus does not grant the right to judge others for sins you don't have (which leads to a spirit of superiority over others). (Romans 2:1-3)

How you handle people's sins will show if you are truly humble in spirit or have a superiority complex. Be careful about creating your own standards of right and wrong.

In things essential, let there be unity. In things indifferent, let there be liberty. But in all things let there be charity (love). (Romans 14). If it's an issue that can't be settled through the scriptures (therefore probably not essential), then use love in your approach; otherwise you're placing your own judgement as wiser than God's laws.

Don't be judgemental, rather be patient with new believers. Also, remember your own path to God when it comes to judging those that have not yet accepted Jesus.

Spend more time with God and become more merciful as you're one who has been shown much mercy.