Include Custom Post Type Posts in Index/Loop

Drop this code in the functions.php, and dont forget to change custom_post_type on line 6 with the name of your post type.

add_filter( 'pre_get_posts', 'my_get_posts' );

function my_get_posts( $query ) {

	if ( is_home() && $query->is_main_query() )
		$query->set( 'post_type', array( 'post', 'custom_post_type' ) );

	return $query;
}

Source