I’ve never prayed with a complete and utter stranger before, but lately my life has taken such unpredictable directions that I hardly blinked when a technician installed a new thermostat — and then asked, “Is it OK if I pray with you?”

He knew I was grieving, which is why he made this unexpected offer — and I quickly accepted. Before long, we stood in my dining room as he fervently beseeched our heavenly father to give me peace of heart.

And, really, isn’t peace what we all crave beneath the relentless rush of everyday life, the woes at work — and the arguments that sometimes shatter our serenity?

In a wonderful movie, “War Room,” an elderly widow named Miss Clara meets an elegantly dressed real-estate agent — Elizabeth — and immediately detects turmoil within the young woman’s heart.

We soon discover Elizabeth dwells in a luxurious home with her handsome husband, Tony, but the twosome are constantly at each other’s throats, bickering about everything — while their little girl quietly cringes.

These folks have everything — sleek cars, trendy clothing, sparkling health — but they lack the essential thing, which is peace. In one poignant scene, the daughter admits that she’d rather live at her best friend’s home, since her own parents are always sparring.

Miss Clara, a total stranger, gradually takes Elizabeth under her wing, confessing that her own marriage long ago was also stormy — until she realized her true adversary was not her husband.

The real enemy is described vividly in “The Screwtape Letters,” where C.S. Lewis presents imaginary correspondence between two demons, demonstrating the invisible war being waged every moment of the day — with the prize being the human soul.

Miss Clara has set aside a special area — her “war room” — where she battles the devil through prayer and Scripture readings. Inspired by this stranger’s example, Elizabeth empties out a large closet in her house, where she, too, hunkers down daily to pray.

Prayers gradually transform Elizabeth from a bitter wife always primed for a fight to a humble woman whose sole desire is a peaceful home. The turning point for the family comes when Tony discovers the closet — and his name on Elizabeth’s prayer list.

As for me, I’d like to tell you the technician’s petitions were instantly answered and all the shards of my heart mended — but that wouldn’t be true.

Still, when this fellow passionately beseeched God for me, I felt the darkness of grief momentarily dissipating. And, upon leaving, when he promised to add my name to his church’s prayer list, I thought about all the strangers whose prayers may change our lives.

As St. Paul so beautifully put it, “Do not neglect to show hospitality to strangers, for thereby some have entertained angels unawares.”