Add the below code in your FTL from to embed web content in theme:
<#assign preferences = freeMarkerPortletPreferences.getPreferences("portletSetupPortletDecoratorId", "barebone") />
<@liferay_portlet["runtime"]
defaultPreferences="${preferences}"
instanceId="Unique_ID_Here"
portletName="com_liferay_journal_content_web_portlet_JournalContentPortlet"
/>