Template Tag Does Not Work in Page Template

The reason your post is not displaying properly is because functions such as the_title(), the_permalink(), and the_content() ( called Template Tags ) can only be used whenever inside “The Loop” or whenever set up properly. There are two options to display your content properly:

Functions: get_post(), setup_postdata() and wp_reset_postdata()

First you would need to get the WP_Post Object and pass it into the setup_postdata() function so that WordPress can setup the template tags to pull in the correct content. Finally, we would need to reset the global $post object by calling wp_reset_postdata().

global $post;               //  Get the current WP_Post object.

$post = get_post( 129 );    // Get our Post Object.
setup_postdata( $post );    // Setup our template tags.

if( 'publish' == $post->post_status ) {
    the_content();
}

wp_rest_postdata();         // Reset the global WP_Post object.

Tad Easier using apply_filters()

This is a little more straight-forward and doesn’t require so much code which is nice. You won’t have access to Template Tags like you would in the above example but if you’re just displaying the post content and processing their shortcodes you won’t need Template Tags.

$post_id = 129;

if( 'publish' == get_post_status( $post_id ) ) {
    $post_content = get_post_field( 'post_content', $post_id );
    echo apply_filters( 'the_content', $post_content );
}

The above grabs the content from the database then runs it through a WordPress filter which processes the_content() hook to give us our desired output, shortcodes processed and all.