Display the content of one page in another page.

functions.php

function get_post_page_content( $atts ) {
	
     extract( shortcode_atts( array(
          'id' => null,
          'title' => false,
     ), $atts ) );

     $the_query = new WP_Query( 'page_id='.$id );
          while ( $the_query->have_posts() ) {
               $the_query->the_post();
                    if($title == true){
                         the_title();
			        }
			        the_content();
          }
     wp_reset_postdata();

}
add_shortcode( 'get_content', 'get_post_page_content' );

The shortcode is:

[get_content id="" title= /]

Where id is the id of the page. The id of the page goes inside the quotes. The id must be set.

title is false by default. Set the value of title to true, if you want the title of the page you are including to show.