How can I put a custom field as the link of a button shortcode?

I think the problem is not with shortcode but with your code – you can’t nest blocks 😉

This should work just fine, I guess:

<?php echo do_shortcode("[standout-css3-button href="". get_post_meta($post->ID, "church-website-url', true) ."']Church website[/standout-css3-button]"); ?>

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)