en_tn/1co/15/15.md

Paul continues to address the lie that Christ was not raised from the Dead.

And we are found to be false witnesses about God

Paul is arguing that if Christ was not raised from the dead then they are bearing false witness, or lying about Christ having been raised from the dead.

your faith is in vain and you are still in your sins.

Paul is saying that since their faith is based on Christ rising from the dead and if that did not happen, then their faith is useless.