Sometimes fully aware of it, sometimes without realising it, we have all stood in opposition to God. We have expressed that in the way we treat God directly, not treating him as God. But we also express it in the way we treat other people, in the way we treat the wider creation, and even in the way we treat ourselves.
The basic problem is that we act in our own interests first of all. We don't treat God as God. We don't treat other people as fully human, although they too are made in the image of God (Gen 1:27). We don't care for the rest of creation benevolently, as God would, although we were commissioned to care for it after His likeness. An everyday word for this is 'selfishness', but the bible calls it 'sin'. This puts blockages, tension, stress and even violence into our relationships, as we all act in our own interests over against each other.
Like a loving father watching his children as they disobey him, hurt each other and tear down the house, the bible tells us that God is angry with us for our sin. He is angry not in spite of his love, but precisely because of it. If he didn't love us, he wouldn't care what we did to each other! But he does care about what we are doing to ourselves and to each other and to his creation at large. He wants to restore harmony, to reconcile each one of us to himself, to each other and to the creation.
Indeed God loved us so much that he sent his Son, his eternal Son who shares in his very nature as God (Heb 1:3; Col 1:15), to become a human being in the person of Jesus Christ (John 1:1-18). Jesus lived a perfect life of obedience to God and love for others even to the point of giving his own life (Heb 4:15, Eph 5:2). By doing so he showed us not only what God is like, but also what we should be like as creatures made in the image and likeness of God. So he called us to follow in his footsteps.
By giving himself up to death on the cross, Jesus accomplished lots of things for us which the bible talks about in several different ways, but the essential result is that there is no longer a barrier between us and God. Jesus defeated sin and death and heralded God's future of a perfect, new humanity living in a perfect, new creation. He did this by rising again from the dead: the first person to be made new.
Jesus invites us to shelter in him, to put our trust in him for a glorious future rather than fighting for space in an ephemeral present. Another word for 'trust' is 'faith'. As a result of what Jesus did on the cross, God is able to group those who trust in Jesus with him and call us 'righteous' also, to regard us as without fault before him despite our many sins. Our lives may be full of regrets, but God holds out forgiveness and a fresh start to anyone. Anyone can take hold of this simply by putting their trust in Jesus.
When we trust in Jesus like this, we are not left the same, but are changed. As our eyes are fixed on Jesus, the perfect image of God, we discover more and more how beautiful God is, and the very things we find attractive, the very things we think matter most, are radically altered. We learn from Jesus how to honour God as God, and to "treat others as more important than ourselves". Our very desires are changed, gradually, to find our own selfishness distasteful and a life of love - the true opposite of a life of sin - to be a wonderful release of our own true selves.
That is why Christians gather to worship regularly to hear God's word and receive the Holy Communion, and why we seek to read our bibles and pray as much as possible. It is these instruments of encountering Jesus in word and action, instruments fired by the power of the Holy Spirit, which are God's way of changing us to be people who will fit into his new creation, "where righteousness is at home".