Yes!  All you need to do is include an  <iframe> in your webpage, and use the parameter embed=true in your online giving URL.  You can find your online giving URL in the Dashboard under My Account > Settings.

Here's an example of and iframe with the embed parameter:

<iframe src="https://churchgiving.online/organizations/abc/online_giving_logins/new?locale=en& embed=true" frameborder="0" scrolling="no" allowtransparency="true" style="width: 100%; height: 1200px;"></iframe>

Adding the  embed=true parameter will remove the header that's normally present and will allow it to fit nicely into your existing website.