Still groggy from the anaesthesia, I was ushered into a small, lifeless room where I was given the news. They'd found a large tumour that was either cancer or lymphoma. No third option.

Just six weeks before, on New Year's Eve as partygoers pulled poppers and drank champagne, I watched my sister lose her battle with cancer. Eight years before that it had taken my mum. But all I said was, Oh.

As the drugs wore off and I was rushed through biopsies, oncology appointments and scheduled for surgery, radiation and chemo, the reality of my diagnosis finally began to sink in. What on earth was God playing at?

We'd moved our family to America to plant a church, hadn't I done enough for him? Was he mad at me? Perhaps he didn't care as much as I thought. Maybe he was off helping someone more spiritual than me who didn't think praying for a parking space made up for a missed quiet time or screamed at her kids on the way to church.

As my world shook, so did everything I knew and understood to be good and true. It felt like I was drowning, gasping for air. I latched onto anything to keep me afloat and explain why the ground was swallowing me whole.

I knew in my head these explanations were nonsense, but to my aching heart they were easier to grasp and made more sense than the alternative – that somehow God was still good, his love for me was as infinite as ever and he knew my deepest longings. The lies, for that's what they were, made sense in the face of my pain. His love didn't.

When our world falls apart or life is messy and overwhelming, we rationalise our suffering with easy-to-believe but incorrect theology. It's a theology that places us as the victim and God as the villain, or at least an uninterested bystander. Nothing is further from the truth. Just because life sucks it doesn't mean God does. Just because we can't make sense of things it doesn't mean they are senseless.

My cancer wasn't lung cancer like my mum's and my sister's, mine was rectal cancer. Yes rectal, and when you have a tumor the size of a fun-size KitKat up where the sun doesn't shine it focuses the mind. I had to decide what I believed about God and how he felt about me. Did I believe these lies or did I believe what his word says. Would I believe my pain or the pain Jesus suffered on the cross for me? At the end of the day, however great or painful life is, it's a decision we must all make.

So, what do you believe?

God's forgotten you, or he'll never leave you (Deuteronomy 31:8)?
He's mad at you and doesn't care, or you're forgiven and his love is unconditional (John 3:16)?
You've got to fight this alone, or he will fight for you (Exodus 14:14)?
He is no help so you need to be strong, or he is with you and will help and strengthen you (Isaiah 41:10)?

In my darkest moments, hooked up to clear IV bags of cancer killing drugs, or fighting an ostomy bag with a mind of its own, I had to decide. Each day, and often each minute, I had to chose to believe that God is my rock, my salvation, my fortress, and my strength, and even as my world crumbled, with him, I would not be shaken (Psalm 62). Sure I wobbled, a lot. But each time I chose to believe the truth about God, who he is and who I am to him, the power of those lies to completely flatten me faded.

No one gets to skip the tough stuff in life and even if you're not battling rectal cancer, I'm sure you've got something keeping you awake at night or overwhelming you in some way and when life stinks it's completely normal to think these things. In fact, these thoughts seem to be our default setting, our go-to explanations, so we must intentionally reset our thinking if we are to conquer the lies and not spiral into self-pity. By saying these truths out loud and asking for his help to believe them when we struggle we can do just that.

Ask yourself this: which is my go-to explanation when life's hard? Why do I believe this and what scripture counters it? Am I willing to intentionally chose to believe God's truth over the lies?

Repeat the scripture daily and every time you find yourself thinking he's mad, doesn't love you, or has forgotten about you. Hold on to to his truth. It will steady you, holding you firm as your world shakes. He loves you and he's not going anywhere. There's no third option.

Niki Hardy has left rectal cancer behind ;) and now offers encouragement, resources and a large dollop of reality on her website, or find her on Instagram (@niki.hardy)