“Sickness is always a curse.“
This false belief was directly refuted by the illness of Job, who was not cursed but was allowed by God to be physically afflicted by Satan.
Then the Lord said to Satan, ‘Have you considered my servant Job? There is no one on earth like him; he is blameless and upright, a man who fears God and shuns evil. And he still maintains his integrity, though you incited me against him to ruin him without any reason.’ ” – Job 2:3
To say a physical affliction the result of sin? Sometimes yes; sometimes no. Based on the Bible, sickness can be the consequence of sin or can be permitted by God to accomplish His higher purpose.
• a result of sin:
“Therefore, whoever eats the bread or drinks the cup of the Lord in an unworthy manner will be guilty of sinning against the body and blood of the Lord. A man ought to examine himself before he eats of the bread and drinks of the cup. For anyone who eats and drinks without recognizing the body of the Lord eats and drinks judgment on himself. That is why many among you are weak and sick, and a number of you have fallen asleep.” – 1 Corinthians 11:27–30
• not of sin:
“As he [Jesus] went along, he saw a man blind from birth. His disciples asked him, ‘Rabbi, who sinned, this man or his parents, that he was born blind?’ ‘Neither this man nor his parents sinned,’ said Jesus, ‘but this happened so that the work of God might be displayed in his life.’ ” – John 9:1–3