thank you very much for your question.Are you telling me that your church uses the Greek Concordance as a Bible?
Please tell me what Bible your church uses then we will see what John and Mark actually wrote.
All the churches I used to be in had German Bibles.
It's just me who uses Greek concordances. However, many people say Bible can'tg be true due to translation issues or cultural influences.
So, if a point of contention arises, I personally use Greek concordances here. For me, it's the Koine Greek text that is flawless for NT.