my brother in Christ

From my + brother in Christ. The phrase was in use unironically for softening the delivery of a harsh truth and discouraging the shooting of the messenger before it ever was used sarcastically as an internet meme; it pursued those aims by emphasizing spiritual fraternity between speaker and listener (compare the theme that you know I love you, but you need to hear the truth).

my brother in Christ (plural my brothers in Christ)

1. (Internet slang) A (sometimes condescending) term of address, used before a statement which intends to dispel someone's lack of self-awareness.

   Hypernym: brother

   Tech bros sometimes say they're against so-called social engineering; my brother in Christ, your technological innovations have been a chief wellspring of such reengineering.

2. Used other than figuratively or idiomatically: see my,‎ brother in Christ.

   Hypernym: brother

   We all must labor in the vineyard and walk in the ways of the Lord; my brother in Christ, you won't find happiness at the bottom of a bottle.

   • 1912 [1911], Gerhart Hauptmann, translated by Thomas Seltzer, The Fool in Christ, Emanuel Quint: A Novel‎^[1], New York: B.W. Huebsch, pages 219-220:

     "But you admit," Brother Nathaniel rejoined, "that they attacked you because the devil moved you, to blaspheme our Saviour, to blaspheme by saying something I can scarcely repeat, that you are more than Peter and nothing less than He Himself, the Lord, the Christ, the Son of God. Tell me, is the report I heard correct?"
     "First, Nathaniel, my brother in Christ, you tell me, you who once baptised me with water, if I in return should baptise you with the Holy Ghost?"
     This utterly alarmed the poor lay-brother.
     "No!" he exclaimed. "Don't speak to me of baptism! Spare me your baptism! I have enough to repent, enough to do to wipe from the book of my sins that morning on which I in my blind trustfulness sprinkled you with water. I don't want your baptism."
     Nathaniel sprang up from his chair.
     Emanuel turned white to the very finger-tips of his long, nobly formed hand, and gazed into the open, his lips trembling. […]
     "Emanuel!" [Nathaniel] cried at last, no longer severe, but full of compassion. "Emanuel," he besought him, "turn from the way you are going if only for my sake, for me from whom God will demand your lost soul on the day of days. You spoke of the mystery of the kingdom. My hair is standing on end, Emanuel. Let us pray that God remove from you this spirit of mental darkness. The mystery of the kingdom is the Lord's."

• Despite using the word brother, this term is often applied regardless of gender. The female equivalent my sister in Christ is occasionally used for women, while the gender-neutral equivalent my sibling in Christ is rarely used.
• This term, like various others from Christianity (such as God bless you and God love them), is sometimes used by non-Christians or cultural Christians rhetorically, without necessarily literally denoting religiosity.

• "My Brother In Christ, You Made This A Meme", Vice, March 23, 2022