A message processing device for processing messages has at least one reception buffer, a message includes at least one authentication element and one message content. The message is received and stored in the reception buffer. A characteristic variable of a priority for security checking of the message is determined as a function of the message content. A processing sequence for further message processing for the security checking, taking into account the at least one authentication element of the messages in the reception buffer is defined and carried out as a function of the characteristic variable.