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.