Theodore L. Cuyler's words ring true when held up against the light of God's Word:
Is any one of you sick? He
should call the elders of the church to pray over him and anoint him
with oil in the name of the Lord. And
the prayer offered in faith will make the sick person well; the Lord
will raise him up. If he has sinned, he will be forgiven. Therefore
confess your sins to each other and pray for each other so that you may
be healed. The prayer of a righteous man is powerful and effective. — James 5:14-16
Mind you, that's not our righteousness, but the righteousness of Christ that we receive through his saving blood. But go back a moment to Cuyler's words, which speak of a right spirit. This is different than the righteousness of Christ. He's speaking of our motivation.
No matter how we might couch our words to those around us and even to God, he sees the motivation of our hearts. If we come to God in prayer for our unsaved loved ones, asking for their salvation in order to suit our own needs, then our motivation is off, and we aren't praying in a "right spirit." That doesn't mean God will prevent our loved one from coming to Christ, but we know God is perfect in his timing. He won't allow something to pass if the circumstances aren't the way He wants them.
What I'm saying here is this. That until we can pray for our spouses out of pure motivation—from a selfless love and desire to see them know our amazing God and all the extraordinary knowledge, peace, understanding, forgiveness, and completeness that comes with it—we, the believing spouses, are the ones God will work on first.
We cannot change our spouses, but we can influence them. Thus God will work in us to change and mold our hearts and character to make us the kind of influence God wants in our spouses lives. God will create us to be whatever tool necessary in instrumenting a change in our loves ones live. And though we are changed, we are still merely the tool, wielded by the great Carpenter.
Herein lies the key to what Lynn and I call thriving in our spiritually unequal marriages. It is not we who are attempting to change our spouses, but God in us, given free reign through our obedience to do whatever is necessary.
Praying and believing,