In the absence of God, full relationship harmony as divinely intended, can never be achieved as long as one is for God and the other is not; there will always exist a roadblock; a resistance; some form of caution or red-flag, or perhaps topics not up for deep discussion, as a direct result of the disharmony that exists because of the sin of disobedience, leading to the sin of death (murder), that entered the world immediately after creation.
a. An orderly or pleasing combination of elements in a whole b. A relationship in which various components exist together without destroying one another c. A relationship characterized by a lack of conflict or by agreement, as of opinion or interest: family harmony.
This post could easily take on an exhaustive approach around the a. & b. definitions for example, taking into consideration that the universe harmony addressed and/or sought out by spiritualists, yoga, or say nature enthusiasts, is immediately discredited by b. definition alone, over a., for the simple reason that in order for perfect (divine) harmony to exist, there can be no death or destruction - and that was lost in the Garden of Eden, contrary to propagated belief, resulting from century old demonic manipulation, necessary for truth (good), to become the lie, and the lie (evil) to become truth.
To close out this latter point that could become a book in itself, as of April 2022, if mercy is shown, the world may be exposed to far more demonic evil than it's prepared for; the news behind the truth of the PlanDemic, disguised as a pandemic, will more than rival Hollywoods best fiction, let alone expose them for their own grotesque role played, responsible for the death of millions of innocent lives.
Going back to the relationships noted at the opening paragraph, the God thing can also take on many twists in a relationship, even when both parties know Jesus Christ in a faithful relationship (born-again), but because of pride fighting the ongoing battle of good verses evil within all people, yet only recognizable by born-again Christians, the devil does what he does best, stealing, killing, and destroying all that is good, especially Christian relationships.
The Apostle Paul speaks of these challenges in Galatians 5:16-26 (leaving out V-18 + V-23b to avoid theology confusion), entitled 'Living by the Spirit's power,' to help us understand the ongoing battle between good & evil - and more so for the Christian who knows what is taking place, because of their faith that opens their eyes to the evil that cannot be seen by those who do not know this Jesus - and this is Paul's teaching:
[So I say, let the Holy Spirit guide your lives. Then you won’t be doing what your sinful nature craves. The sinful nature wants to do evil, which is just the opposite of what the Spirit wants. And the Spirit gives us desires that are the opposite of what the sinful nature desires.
These two forces are constantly fighting each other, so you are not free to carry out your good intentions.
When you follow the desires of your sinful nature, the results are very clear: sexual immorality, impurity, lustful pleasures, idolatry, sorcery, hostility, quarreling, jealousy, outbursts of anger, selfish ambition, dissension, division, envy, drunkenness, wild parties, and other sins like these. Let me tell you again, as I have before, that anyone living that sort of life will not inherit the Kingdom of God. But the Holy Spirit produces this kind of fruit in our lives: love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. Those who belong to Christ Jesus have nailed the passions and desires of their sinful nature to his cross and crucified them there.
Since we are living by the Spirit, let us follow the Spirit’s leading in every part of our lives. Let us not become conceited, or provoke one another, or be jealous of one another.]
End of Paul's teaching!
So, you see the two key points highlighted, the two forces (good & evil) constantly fighting against each other - and then, as long as we allow the discouragements of the world (devil stealing, killing, & destroying all in his path - John 10:10), continue to beat us up, rather than trusting in the inerrant and infallible living word (Holy Bible) of Jesus Christ Living God, keeping Him as #1, not our spouse, children, friends, the universe, etc., but Jesus as #1, then and only then can we become the best spouse, parent, friend, co-worker, etc., and call not on the universe for our strength, but on the ONE who spoke that universe into being.
In closing, can we have a great relationship without God, yes of course, but if you're living in a relationship rated at say even 8 out of 10, why not 10? And why not live even though you die, rather than one time around without Christ?
John 11:25 tells us: "Jesus told her, “I am the resurrection and the life. Anyone who believes in me will live, even after dying."
PS: comparing the graphic below, undeniable beauty by intelligent design, to the one above when God is kept out of the picture, leaves only the world to count on, believing in anything and everything but Jesus Christ - below is He at work - above is evil at work - our choice!