Let your light shine before others, so that they may see your good works and give glory to your Father who is in heaven. (Matthew 5:16 ESV)

But when you give to the needy, do not let your left hand know what your right hand is doing, so that your giving may be in secret. And your Father who sees in secret will reward you. (Matthew 6:3-4 ESV)

A friend recently posed these two verses to me and asked, “So when do you tell others about your good deeds and when do you not?”

It’s a good question.

I believe the contexts of these verses give us the clues. Jesus is addressing the two-sided coin of human pride.

In Matthew 5:16, Jesus is addressing our fear of man. The context is that we are blessed when reviled and persecuted (v.11). The good works Jesus has in mind here are the kind that the prophets did (v.12). They testified to God’s word openly. In other words, don't be ashamed of the gospel (Romans 1:16) or any acts of love that testify to it, even when the threat of persecution is present. 

In Matthew 6:3, Jesus is addressing our selfish ambition. The context is people (in this case, the rich) who were marketing their acts of charity to enhance their personal brand. In other words, they were seeking human admiration. That's not love of God or the poor. It's self-worship. 

So a rule of thumb in shining and hiding: good works we are tempted to hide for fear of man’s disapproval are likely ones we should let shine. Good works we are tempted to do publicly for man’s approval are likely ones to keep secret. Both kinds of good works encourage humility and kill pride.