According to Islamic teachings, if a Muslim is invited to a gathering where alcohol is served, the appropriate response is to:

– Decline the invitation if possible
– If attendance is necessary, avoid participating in any haram (forbidden) activities, including drinking alcohol
– Try to excuse yourself from the area where alcohol is being served
– Engage in halal (permissible) activities and maintain good company

Remember, a Muslim is expected to avoid situations that may lead to haram activities. If in doubt, consult with a knowledgeable Islamic scholar or Imam for guidance.