Single page site (WordPress) including posts

To include posts and pages in the loop, use the ‘post_type’ argument:

<?php
$wp_query = new WP_Query();
$args = array(
     'post_type' => array('post','page')
);
$wp_query->query($args);
while ($wp_query->have_posts()) : $wp_query->the_post();
?>

<?php the_content(); ?>

<?php endwhile; ?>

http://codex.wordpress.org/Class_Reference/WP_Query