<input name="fromName" id="fromName" value="{% if message is defined %}{{ message.fromName }}{% endif %}" type="text">

<input name="message[Phone]" id="phone" type="text" value="">

{% for course in courses %}
    <input id={{ course.slug }}" name="message[Course]" type="radio" value="{{ course }}"
         {% if message is defined and message.message[Course] == course %}
             checked="checked"
         {% endif%}>
{% endfor %}

Variable "Course" does not exist.