Steadfastness

For though I am away from you in body, yet I am with you in spirit, delighted at the sight of your [standing shoulder to shoulder in such] orderly array and the firmness and the solid front and steadfastness of your faith in Christ [that leaning of the entire human personality on Him in absolute trust and confidence in His power, wisdom, and goodness]. Colossians 2:5 (AMP)

Steadfastness of your faith in Christ. 

Steadfastness: unwavering, adherence, faithfulness, determination, fortitude, moral fiber, resolve, tenacity

As I studied this verse, I couldn't have explained the truth better than John Gill's did here: 

and the steadfastness of your faith in Christ;

either in the grace of faith, and the exercise of it on Christ, in opposition to doubtings and unbelief; whereby God is honoured, and with which he is well pleased; souls are filled with peace and joy; Satan is resisted and overcome; and the hearts of others, particularly ministers of the Gospel, are comforted: or in the doctrine of faith respecting Christ, in which they stood fast; notwithstanding there was a majority against it, the wise and learned, the rich and mighty, did not receive it; and though it was opposed by false teachers, persecuted by profane men, and loaded with reproach and obloquy; and also in the profession of it, which they held without wavering: now to see a set of Christians, a church of Christ walking together in Gospel order, steady in their faith on Christ, abiding by the doctrine of faith, and maintaining an honourable profession, how beautiful and delightful is it! John Gill's Exposition of the Bible

What a great testimony... steadfastness of your faith, whereby God is honored, and with which he is well pleased; souls are filled with peace and joy. 

And that is only possible, when hearts are permeated with a deep sense of reverence for God (Acts 9:31; MSG).