"What's your sign?" How can a Christian use this question to open a conversation that lovingly explains the dangers of astrology and horoscopes?
What an interesting question!
I can imagine a response that includes statements like these: “My sign is the cross of Christ.” “I trust the God who made the stars and holds the future in his hands.” Bible passages that could accompany those statements are Galatians 6:14, Genesis 1:16, Psalm 8:3-4, Psalm 139:16 and Isaiah 46:10.
With a little more explanation from the Bible, you could let questioners know that you follow the “star of Jacob” (Numbers 24:17). That prophecy pointed to Jesus Christ.
You have the right approach in that you want to “open a conversation” on the subject of astrology and horoscopes. At some point you can explain how the Bible warns of those practices (Leviticus 19:31; Deuteronomy 4:19, 18:10-12).
God bless your testimony of Christian faith!