The contrast in verses 27 to 36, that is to say in the whole of John's answer, is a contrast regarding the statement made in the first place, in verse 26 :
... behold the same baptizeth and all come to him.
και παντες ερχονται προς αυτον
Here, pantes is the nominative plural of pas. In the verse under question, verse 35, pantas is the accusative plural of the same word, pas.
In the KJV, the plural word is translated 'all' 541 times, 'all things' 150 times, 'all men' 36 times, and sundry others a dozen times [Young's Analytical Concordance].
The KJV, in verse 26, puts the word 'men' in italics after 'all'. But the KJV then adds the word 'things' in verse 35 without adding italics, which is slightly confusing.
Tyndale, Young's Literal, Green's Literal, the EGNT, The Wycliffe and J N Darby all state 'all things' in verse 35 but it has to be noted what John the Baptist has actually said in response to the original statement.
John, in response to the words 'all come to him' says, verse 32 :
... what he hath seen and heard, this he testifies; and his testimony no-one receives . . . . . . [EGNT literal interlinear]
'No-one', here, is ουδεις oudeis.
The context, and the contrast, is of a question which arose between John's disciples and the Jews about purifying in verse 23. And the context of that controversy was John baptising in Aenon, near Salim, where there was much water.
And previous to that, is the context of Jesus and his disciples coming into the land of Judaea and baptising, when John was already baptising in Salim.
So ... John baptising where there was much water, Jesus baptising, (John not yet cast into prison), a question between John's disciples and the Jews about purifying ...
... then a statement, seemingly provoked by the Jews altercation with John's disciples regarding purification.
John's response is to diminish himself, verse 29 and again verse 30. And to exalt the One from above, verse 31. Then he focuses on His testimony - where it came from and who receives it.
Then he focuses on Whom that One from above is - whose words he speaks - what Spirit he speaks by - what relationship He has with God almighty - and what will be the final outcome of it all.
The culmination of John's words is this :
He that believeth on the Son hath everlasting life; and he that believeth not the Son shall not see life, but the wrath of God abideth on him.
The destiny of all is decided, either by the fact of their faith - in Him.
Or by the fact of their unbelief - of Him.
All are delivered into his hand.