Not the Doing, But the Resting In

Should Christians be earnest about building into their lives the disciplines of prayer, giving, Bible meditation, church involvement, regular confession of sin, etc? Does such earnestness jeopardize one's grasp of the gospel?

I am increasingly convinced that healthy spiritual disciplines and healthy gospel-centeredness rise and fall together.

In Edward Fisher's The Marrow of Modern Divinity, the character Evangelista (= mature Christian) is explaining to Nomista (= legalist) that upholding the full and free gospel of grace does not undercut violent-if-need-be development of habitual spiritual exercise: 

Mistake me not, I pray, in imagining that I speak against the doing of these things [religious exercises], for I do them all myself, but against resting in the doing of them, the which I desire not to do. (p. 257)

Now there's a sentence for all of us who have given the current gospel-mega-surge any thought at all, whether of cynicism or of exultation.

Evangelista goes on to explain why this distinction is important:

Man's poor soul is not only kept from rest in God by means of sensuality, but also by means of formality. If Satan cannot keep us from rest in God by feeding our senses with our mother Eve's apple, then he attempts to do it by blinding our eyes, and so hindering us from seeing the paths of the gospel. If he cannot keep us in Egypt by the flesh-pots of sensuality, then  will he make us wander in the wilderness of religious and rational formality. (ibid)