Growing up in a religious family that believed in working hard to be on good terms with God, Isaiah Mwewa still questioned whether or not he would go to heaven when he died.
Isaiah was already reading religious material at age seven and says he thought this, and doing good deeds, was the only way to please God.
"Then, when I was 20, I began to feel troubled because I didn't know how I could be sure of my salvation," Isaiah says.
Those around him said there was no guarantee of going to heaven – he could only hope his good deeds outweighed his bad deeds.
Nearly a decade later, Isaiah married a woman who went to a Christian church, one where the people believed salvation was 100 per cent guaranteed through faith in Jesus Christ.
"I started following my wife to this church and for the next nine years I heard about God's way of salvation, being born again of the Spirit of God, as the Bible clearly teaches," Isaiah explains.
During this time Isaiah says he learnt where he stood in God's sight – that no matter how many good deeds he may do, he still could not meet God's perfect standard to get into heaven.
But I also came to know that God wanted to have a relationship with me. He wanted me to accept that I am a sinner but also that Jesus had opened a way for me to be saved, by believing Jesus had taken the punishment I deserved for my sin on the cross."
He was further convinced by this church's beliefs after reading in the Bible from Ephesians chapter 2 verses 8 and 9 which says, "God saved you by his grace (undeserved kindness) when you believed. And you can't take credit for this; it is a gift from God. Salvation is not a reward for the good things we have done, so none of us can boast about it."
"As I listened and read my Bible, I became convinced that Jesus had given His life, He had spilled His blood, for my sake and for all who would trust in Him," Isaiah says.
"So, after fully understanding this, when I was 40 years of age, I confessed that I am a sinner and received Jesus as my Master and Saviour."
After this, Isaiah says Jesus changed Him by giving him a hunger for God's true Word, the Bible, and the desire to obey Him every day. Out of this has come a strong desire to help the poor and tell people about Jesus.
He continues: "I love to tell others the love of Jesus, especially other workers at the mine where I am employed. I am a happy person now, whether as a husband, parent or at work."
Despite his commitment to God, Isaiah and his family still faced many difficult times. They lost three children, which to some may be a reason to reject God, but Isaiah has a different perspective.
"The Lord Jesus has helped my wife and me, through all these difficult times," he explains.
"He has provided me and my family with many things. He gave me time to pray to Him at work, even as I was promoted to a higher position. I know it was also God's grace that I came back to health after the many illnesses I have passed through."
Though Isaiah does not know why his children had to die, he and his wife stand firm in their faith, knowing they are certain to see their children again in heaven one day.