how do you know if someone is a christian?
I don’t know, only God know whether someone is a true christian or not, for there’re false brothers in the Church.
Jesus said through their fruit you can know the tree. I think a true Christian should live with the characteristics of Jesus.
God’s words will reveal the heart of a person. Paul knew who were false brothers. Why? Through the word of God. We need to know the word of God deeply.