A doctrine is a teaching of the Magisterium. A dogma is an infallible teaching of the Magisterium. A dogma is an infallible doctrine. All dogmas are doctrines; not all doctrines are dogmas.
The Magisterium teaches infallibly in any of three ways:
1. solemn definitions of the Pope
2. solemn definitions of an Ecumenical Council
3. the ordinary and universal Magisterium
All other teachings of the Magisterium are non-infallible and non-irreformable. The infallible teachings are guaranteed by the work of the Holy Spirit to be true and without error. The non-infallible teachings are guaranteed by the work of the Holy Spirit to have only a limited possibility of error, such that no error or set of errors could lead the faithful away from the path of salvation.
The infallible teachings require the full assent of faith (theological assent or ‘sacred assent’). The non-infallible teachings require the religious submission of will and intellect (‘ordinary assent’). Dissent from any infallible teaching is the sin of heresy. But some faithful dissent from particular points within non-infallible teachings on a matter of faith or morals is possible, because those teachings are not entirely free from error. God who is Truth does not require that we adhere to a falsehood.
The non-infallible teachings are also non-irreformable. To whatever extent a non-infallible teaching may be in error or in some way incomplete, to that same extent the non-infallible teaching is able to be reformed by subsequent magisterial teaching. A non-infallible teaching may be reformed by further clarification, by correction of particular points of error, by further doctrinal development, etc. Sometimes theologians or the laity in general have a role to play in that reform, in that subsequent development of doctrine. But the reform itself is always and only accomplished by the Magisterium.
In any case, non-infallible teachings are not subject to unlimited possibility of error and so are not subject to unlimited possibility of dissent or of reform. The approach of some persons, to misrepresent many different infallible teachings as if these were non-infallible, and then to represent those supposedly non-infallible teachings as subject to complete rejection by the faithful on the basis of a claimed need for reform, is nothing other than unfaithful sinful dissent. In some cases, this approach reaches to the extent of abject heresy. For the teachings that they claim can be rejected as non-infallible are actually infallible teachings. In other cases, even if a teaching of the Magisterium is non-infallible, it requires ordinary assent. The claim that non-infallible teachings, as a body, do not require the religious submission of will and intellect is also a heresy.
Faithful dissent is limited to particular points of non-infallible teachings, those not essential to salvation, and then only when the basis for dissent is Tradition, Scripture, Magisterium — not merely popular opinion, or the reasoning of a fallen human person, or a new philosophical system that is being proposed at the same time.
More on this topic in subsequent posts.
See also this set of online articles:
Insights into Tradition, Scripture, Magisterium