Keep back thy servant from presumptuous sins. Presumptuous sins are sins which arise out of pride and lead to presumption. But after Uzziah became powerful, his pride led to his downfall. Clearly this was a work confined strictly to the priesthood and although he was the King, Uzziah was trespassing on holy ground. The priests did their best to restrain King Uzziah, but it was too late for he was struck with leprosy immediately.
Apostasy is a sin of presumption.
It is a very deliberate sin which keeps on sinning in spite of knowing the truth. It is a terrible sin to treat as unholy the blood of the covenant. The sheer magnitude of what was involved to come into this world and conquer sin for us was daunting to Christ. No celestial being could have done what Jesus did. The finality and glory of his accomplishment is expressed in the words 'he sat down at the right hand of the Majesty in heaven'.