Which denomination: Catholicism, the Church of England, or Presbyterianism, was a threat to James I?

On the death of Queen Elizabeth in 1603, the new Stuart monarch found several varieties of Christianity practised in his three Kingdomes of Ireland, England (and Wales), and Scotland. Which of these denominations posed the greatest threat to the Stuart monarch while James I was in power (1603-25) James himself was Presbyterian, son of Mary Queen of Scots, who was Catholic. But with his laid back attitude towards religion, which one represented the greatest threat?