The Catholic Church is a communion in the spiritual realm that gives no defense against the Devil.
Classical Reformation era Protestantism, as a whole, is a sound fortress in the spiritual realm. It exists as this as something that is not necessarily attached to local communions. Classical Reformation era Protestantism as a whole.
Eastern Orthodox Christianity is pious in some good ways but vulnerable on the spiritual battlefield due to doctrinal ignorance and an acceptance of doctrinal ignorance.
Biblical doctrine is armor of God. This is how it is practical. It is actual armor on the spiritual battlefield. Hard saying, unwatered down, unnegotiated down to the demands of our fallen nature biblical doctrine when seen and accepted and valued changes you internally. It reorientates you. For instance it makes you God centered rather than man centered. Without real biblical doctrine you are naked on the spiritual battlefield. If you don't know what real biblical doctrine is yet then move towards what your fallen nature hates the most. (Yes, real biblical doctrine is five solas, doctrines of grace Calvinism...classical Covenant - Federal - Theology.) Use the same method to find the pure and whole word of God (it is the received Hebrew and Greek text underlying the Authorized - King James - Version, in any sound translation, but notice there's only one available widely today, which is telling).
The use of the Law for a regenerated Christian is for necessary friction for inner spiritual development (progressive sanctification). The friction comes not just from the Law in it's pure form (there is less friction there for a regenerated Christian because a regenerated Christian can follow the law and wants to follow the law), but also from the Law in its twisted, distorted form. The Devil, the world (including other human beings), and our inner fallen nature twist the Law of God and distort it to make it a mass of accusation and shaming and policing in the service of maintaining the elements of Devil's Kingdom here in this world. After the Fall, the pure Law of God came into the hands of the Devil, the world, and our inner fallen nature...mass fallen humanity, and has been twisted and distorted and turned into a works righteousness as defined by the Devil...with the Devil's goals in mind. This twisted, distorted aspect of God's Law is like a massive black monstrous presence in this world working to keep individuals in their place (in the Devil's Kingdom) and working to feed the Devil's Kingdom with suffering and death. To see it in full manifestation study the hell of the totalitarian regimes of the 20th century. Remember, the mass effecting of this twisted, distorted form of God's Law is acted out by fallen human beings who act with a piousness and Pharisee-like self-rightiousness and sense of being holy that are also distorted aspects of real biblical faith. Of course the Beast and the False Prophet, in their different manifestations, are the objects (idols) of their worship in all this, whether as a totalitarian state, the planet, multi-culturalism, media, entertainment, education, etc.. Seeing all this as God's Law (twisted and distorted) brings you to the practical level of seeing something as big in the faith as the Law in a clear way.
The Gospel is regeneration, justification, repentance, faith, definitive sanctification, adoption, glorification. All that is connection. It's not 'being good.' It is connection. Effected by God. To use a biblical metaphor you *were* a fish, living in a wholly different cosmos (the ocean, or "sea" as the language of biblical prophecy prefers sometimes, and see how 'sea' is not a good thing?). Then you were 'hooked' and drawn up out of that cosmos into a wholly different cosmos, where you exist now (I speak to regenerated believers). So, practically speaking, the 'connection' you have in the Gospel is with a wholly different cosmos you are now living in (your very life force comes from another source, the living water Jesus speaks of). Notice you're a bit out-of-step with your environment? Other people? Alienated? At odds? Even beyond the usual degree of alienation caused by the Fall to begin with? It's because you are not even in the same cosmos they are living in. You are even in another realm of time.