Our thoughts on this can affect our sharing of the Gospel, and it merits a closer look.
“Judge not, lest ye be judged!”
This phrase is often thrown out in haste by believers and non-believers alike when it is brought to their attention that the Bible contradicts something people like to do or think is ok. It comes from the first four verses of Matthew 7.
"Judge not, that you be not judged. For with the judgment you pronounce you will be judged, and with the measure you use it will be measured to you. Why do you see the speck that is in your brother's eye, but do not notice the log that is in your own eye? Or how can you say to your brother, ‘Let me take the speck out of your eye,’ when there is the log in your own eye?" - Matthew 7:1-4
Jesus has made it clear. We are not to judge others. Though with multiple definitions for the verb 'judge', which definition are we to avoid out of obedience to Christ?
Jesus is referring to 'passing legal judgment on; passing sentence on'.
When we apply this definition of 'judge' to Jesus' words in the text we rightly see that we are not to pass judgement on others regarding their sin, when in fact we have exact same problem of the log in our own eye, that is, a huge problem with sin we have not asked forgiveness for and are not seeking repentance of.
Many people stop reading at this point in Matthew 7 in the passage thinking they have heard all Jesus has said on judgement. We read on;
"You hypocrite, first take the log out of your own eye, and then you will see clearly to take the speck out of your brother's eye.." - Matthew 7:5-6
So we have another definition of 'judge' that Jesus says we are able to act on without disobeying his words. 'to infer, think, or hold as an opinion; conclude about or assess'. Every time we answer a question or form an opinion of something we have judged or made a discernment.
Now we see Jesus calling us to clear up our own issues first. Having asked for forgiveness, repented of our sins, and walking with Christ, there is a point where we are able to address issues in others and share what the Gospel says about those issues, Knowing when that point is in our lives should be Holy Spirit lead. This type of judgement goes hand in hand with discernment, and is addressed in Scripture. Discerning what is pleasing to the Lord (Ephesians 5:10). Discernment is for mature Christians and is trained by constant practice to distinguish good from evil (Hebrews 5:14).
So, yes, there is a time we judge others. Not by passing a sentence on them, but by holding an opinion on their sin issue that is fully based on the Gospel and how it addresses things, then sharing that opinion of God's Word, with gentleness, respect, and the same grace that was shown to us on the cross. As before this must be completely bathed in prayer and the words to speak sought from the Holy Spirit and the Word.
We cannot let the fear of being seen as judgemental keep us from sharing the truth of the Gospel with those who need to hear it. If they have not, and we do not share, we leave them in condemnation.
Faith comes from hearing, and hearing through the Word of Christ (Romans 10:17).
God's Word should be our only tool in discernment regarding every single thing in our lives as it is perfectly equipped for it.
"For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart." - Hebrews 4:12