Easily the jewel of the 16th-century Reformed confessions is the Heidelberg Catechism, which begins in so memorable and moving a fashion as to work its way into the hearts of believers everywhere:

Q & A 1
Q. What is your only comfort
in life and in death?

A. That I am not my own,
but belong—
body and soul,
in life and in death—
to my faithful Savior Jesus Christ.

He has fully paid for all my sins with his precious blood,
and has set me free from the tyranny of the devil.
He also watches over me in such a way
that not a hair can fall from my head
without the will of my Father in heaven:
in fact, all things must work together for my salvation.

Because I belong to him,
Christ, by his Holy Spirit,
assures me of eternal life
and makes me wholeheartedly willing and ready
from now on to live for him.

Q & A 2
Q. What must you know
to live and die in the joy of this comfort?

A. Three things:
first, how great my sin and misery are;
second, how I am set free from all my sins and misery;
third, how I am to thank God for such deliverance.

The life in Christ is, above all, a life of gratitude for the gift of life itself and for the restoration of that life from the bondage of sin and death through his perfect sacrifice on the cross and subsequent resurrection. Any human effort to find such comfort in something or someone else is bound, as St. Augustine understood, to leave our hearts restless.