writing option re automatic tag nesting missing

Hi Andy,

I know that this might not be the answer that you’re looking for, but if you want functions in your content area, I strongly recommend using shortcodes instead of leaving the markup open and then closing it in the template. Not only does your site become prone to markup mistakes, but also will reduce scalability and compatibility with other plugins (e.g. export / import)

Over all it is just really bad practice, and I urge you again to use shortcodes instead.

Something along the lines of the following:

// This tells WP to register the [my_shortcode] and 
// run igy64326_function wherever it is found.
add_shortcode( 'my_shortcode', 'igy64326_function' );	

// This is the actual function
function igy64326_function($atts){
	
    // start outut buffering
	ob_start();

        // if you need to pass attributes like [my_shortcode x=10 y=5]
	// remove this, if not needed.
	print_r($atts);
	
	global $post; // required
	
	$args = array('numberposts'=>1, 'category'=>75,39,46,23, 'order'=>'ASC');
	$custom_posts = get_posts($args);
	foreach($custom_posts as $post) : setup_postdata($post);?>
	
		<h6 class="home-feature"><a href="<?php the_permalink(); ?>" title="<?php the_title_attribute(); ?>"><?php the_title(); ?></a></h6>
		<?php 
		the_post_thumbnail(); 
		the_excerpt( sprintf(__( 'Read More<span class="screen-reader-text"> "%s"</span>', 'twentyseventeen' ),
		get_the_title()) );  
		?>
		<a href="<?php echo get_permalink(); ?>" class="purplez">
			<?php
				// Keep hardcoded texts translatable
				echo __('Read More', 'twentyseventeen'); 
			?>
		</a>
	<?php  
	endforeach;
    // return output buffer, and clean it.
	return ob_get_clean();

}

I didn’t test it, but it should give you an idea.
You’d need to change the ‘my_shortcode’ to whatever you’d like. Also, you could change the function name to something else, just make sure it’s unique.

Also, check the inline comments.