We always recommend keeping a full backup of your website before you update your theme. This can be done using any of these recommended plugins UpdraftPlus & BackupBuddy

Updating Native Church theme is easy from within your WP Dashboard. Once the Envato Token is added to your WP Dashboard => Born To Give => Welcome page, you will see the available update on this page itself where theme can be updated in a single click.

More details about generating Envato Token can be found here

Using older version(< 2.0) of theme?

The above method of theme update was added in version 2.0 of theme. Users with an older version of theme should use the Envato Market plugin to update their theme. See details here

Note: You can always download the latest version of theme from your ThemeForest’s Downloads page, the installable theme can be uploaded at Appearance => Themes