Hello ChrisMP,

This Worked for me...
Sub Contact_2()

    Dim Con1 As Range
    Dim Con2 As Range
    Dim Con3 As Range
    Dim Con4 As Range
    Dim Msg  As String
    
        With Worksheets("Registration Form")
            Set Con1 = .Range("E53")
            Set Con2 = .Range("E59")
            Set Con3 = .Range("E77")
            Set Con4 = .Range("E81")
        End With
        
        If Application.CountA(Con1, Con2, Con3, Con4) = 0 Then
            MsgBox "Please fill in all required fields"
            Exit Sub
        End If
    
        If IsEmpty(Con1) Xor IsEmpty(Con2) Then
            If IsEmpty(Con1) Then
                Msg = Msg & "Please input the required Con1" & vbLf
            Else
                Msg = Msg & "Please input the required Con2" & vbLf
            End If
        End If
    
        If IsEmpty(Con3) Xor IsEmpty(Con4) Then
            If IsEmpty(Con3) Then
                Msg = Msg & "Please input the required Con3" & vbLf
            Else
                Msg = Msg & "Please input the required Con4" & vbLf
            End If
        End If
    
    If Msg <> "" Then MsgBox Msg
    
End Sub