BuddyPress Lockdown

<?php

// **** Privacy ********
function restrict_access(){
global $bp, $bp_unfiltered_uri;

	// If user is not logged in and
	if (!is_user_logged_in() &&
				(
					// The current page is not register or activation
					!bp_is_register_page() &&
					!bp_is_activation_page()
				)

 		)	{
				// Redirect to registration page. Change /join to your register page slug
				bp_core_redirect( get_option('home') . '/join' );
			}
}

add_action( 'wp', 'restrict_access', 3 );