Doctrine is practical. In scripture we have a pattern of the indicative and then the imperative (see this book for a defense of this pattern). Paul begins his letters stating his doctrinal concerns, then the “therefore…” this is how you should live!
Those who read through systematic theologies know that for the most part, doctrines are stated, but not applied. This is not the case with at least one systematic theology I’m familiar with and use regularly.
While no true lover of books will be satisfied with online material, (come on, you can’t pick it up, you can’t smell the combination of ink and paper); online books are certainly helpful in various ways (size, searchability, etc.).
If I were to recommend one systamatic theology (and that perhaps would not be easy), I would recommend Wilhelmus à Brakel’s 4 Volumes A Christian’s Reasonable Service (here is an alternative place to purchase).
You can currently dowloand (in PDF format) all four volumes by clicking here.
The publisher’s description reads:
Wilhelmus à Brakel (1635-1711) demonstrates one of the strengthsof the Dutch Nadere Reformatie (Second or Further Reformation), namely, the balance between objective truth and the subjective experience of that truth. The Christian’s Reasonable Service is a systematic exposition of Christian doctrine, covering all of the intricacies and debated points of Reformation and post-Reformation dogmatics. This is done is scholastic fashion, with great precision and theological acumen. That being said, it was primarily written for the author’s congregation and is a tremendous work of piety and pastoral concern. Brakel labors to bring practical application to each doctrine he treats, showing the value and use of the truths of God’s Word. It is not enough to assent to right doctrine; one must also engage these truths with hearts of faith and repentance. Let this work be an encouragement to all who read it, and an example to today’s ministers in directing doctrine to its proper end.
The translator of A Christian’s Reasonable Service Rev. Bartel Elshout has a blog, so everything you ever wanted to know about à Brakel, I would recommend you go here.