THE BOTTOM LINE
"Therefore, my brethren, you also were made to die to the Law through the body of Christ, so that you might be joined to another, to Him who was raised from the dead, in order that we might bear fruit for God." (Rom. 7:4). "For sin shall not be master over you, for you are not under law but under grace." (Rom. 6:14).
You can't be joined to Christ and still date your "ex." Three signs that you're committing spiritual adultery with the law: First, you treat commands like they're promises. Promises are for the married, the covenanted; commands are for servants. Promises require faith (Rom. 4:14; Gal. 3:18) -- "evidence of things hoped for" (Heb. 11:1), which means they're futuristic; commands are present responsibilities and require immediate obedience. Promises wait for God to act; commands require us to act. Confuse the two and you'll give off the stale "perfume" (2 Cor. 2:16) of being with another lover.
Second, you relate to God more as a judge rather than a father. The pricked conscience of a judge's verdict far outweighs the joyful heart of a husband's affection. You relate to God's authority far more than to His intimacy. Christians are called to measure God's love (Eph. 3:17ff.), as "Abba! Judge!" doesnʼt make sense.
Third, you mistake the "mushrooms" of the oldness of the letter with the fruit of the newness of the Spirit. Not everything that grows is a sign of life. Zeal for God is no indicator of fidelity to Christ (Acts 21:20; Rom. 10:2). Oldness speaks of the past, our failures; newness speaks of now, Christ's successes. Fruit is found on branches attached to vines; mushrooms on stumps of dead trees -- a poisonous fungus grown in the dark, similar to self-loathing and self-centered testimonies of only how great a sinner we are, instead of celebrating our joy in the Sun of Righteousness (Mal. 4:2).
Never forget that the power of sin is not the devil or the world, but something good and holy (Rom. 7:5; 1 Cor. 15:56). That power is only conquered by living under grace -- the mind set that Christ always loves us not based on how we perform but what He promises. Keep that in your heart and you won't ever be found in the arms of a strange "lawyer."