Include an IF and his corresponding else in PHP

Hi guys I'm trying to do a strange thing, I want put all of my code, of all my website pages inside an if, for example I want do this:

<?php
    include('..../...../php/secure-open.php');
    if(......){
     ALL OF WEBSITE CODE HERE
    include('..../...../php/secure-close.php');
 }

Where secure-open.php is:

<?php
    if(security check here){  
?>

And secure-close.php is

<?php 
    }else{
    die();
    }
?>

So all the will will be executed only if the security condition is true, but when I try to do it, it says, Unexpected document ends on line`....