Hello community,

I need to update a custom field in my standard Contact, that fires after a different, Custom Object is updated, validated by a lookup relationship. (The Custom Object has the Contact, and Contact's Account, listed as Lookups)

I've tried to write a trigger that passes the field value from my Custom Object to the Contact, but I keep getting a variety of errors - the most recent of which has stumped me. The end goal is to update Passing__c from Passing_Field__c. At the moment, the system does not recognize 

p.Passing_Field__c

As a variable, which leads me to assume I'm not identifying the fields correctly to begin with. Is there a better way to do what I'm trying to accomplish here?

trigger ContactUpdater on Custom_Object_Name__c (after update) {

 List<Contact> updatedContacts = new List<Contact>();
 Set<Id> ObjectIds = new Set<Id>();
 Set<String> ObjectCont = new Set<String>();
 Set<Boolean> ObjectActive = new Set<Boolean>();
 Set<String> ObjectPass = new Set<String>(); 

 for(Custom_Object_Name__c p : trigger.new){
     If(p.Active__c == true){ 
       ObjectIds.add(p.Id);
       ObjectCont.add(p.Contact__c);
       ObjectActive.add(p.Active__c);
       ObjectPass.add(p.Passing_Field__c);
 }
 }
    try{
        for(Contact c : [SELECT Id, Passing__c FROM Contact WHERE (AccountId IN (Select Account__c from  Custom_Object_Name__c )) AND ObjectActive = true])
        {
          set(c.Passing__c = p.Passing_Field__c);
          c.FieldToUpdate = c.Passing__c;
          updatedContacts.add(c);
         }
         update updatedContacts; 

}

     catch(exception e){
        throw e;
 }

*Notes: Active_c is a checkbox. Passing_c and Passing_Field__c are both text boxes.*