Achish is forced to pass on to David the decision of the lords of the Philistines. He almost apologises for doing so, and seems to want to assure David that the decision has nothing to do with him.
Sometimes there are people; they are not converted and they seem to be halfway there, and they will use spiritual language and so on, but they are still worldlings; be careful. They are still really on the world’s side deep down. We must wait for God’s salvation to be genuinely worked in them, before we welcome them as fellow believers. So it was with Achish. It was Achish who was going to plan this great destruction of Israel in the battle that followed. He is going to decimate tens and thousands of the Lord's people.