You are insisting on extracting verses 28 and 29 from from their context to avoid admitting that they allow for a different meaning from the one you want to read into them.
Eph. 2:8-9 For by grace are ye saved through faith; and that (touto) not of yourselves: it is the gift of God not of works, lest/that not any man should boast.
Here the neuter "that" (touto) refers back to the clause "you are saved by grace through faith" as being God's gift, followed by the reason, "so that no man should boast."
John 27 Labour not for the meat which perisheth, but for that meat which endureth unto everlasting life, which the Son of man shall give unto you: for him hath God the Father sealed.
28 ¶Then said they unto him, What shall we do, that we might work the works of God?
29 ¶Jesus answered and said unto them, that (touto) is the work of God, so that (hina) ye believe on him whom he hath sent.
Here touto refers back to "Labour not for the meat which perisheth, but for that meat which endureth unto everlasting life, followed by the reason, "so that (hina) ye believe on him whom he hath sent."
Perfectly reasonable exegesis.
Nevertheless, you are free to believe as you wish.
Thanks, Paul for your permission to believe as I wish - I'll probably take you up on that.
And are you sure that you're not avoiding that they might allow a different meaning from what you want to read into them?
Anyway, before I spent time digging into this offline, please answer a few questions for me if you would:
I reviewed 15 different translations of John 6:29. Out of those 15, 12 were exactly or effectively the same as the KJV, 3 were different.
Those 12 uses "this" as in "this is the work of God" - I couldn't find any that use "that" - as in "that is the work of God - your translation above. (BTW 199 times in the KJV touto was translated as "this"; only 22 as "that")
Here are the translations I found:
[Jhn 6:29 NKJV] 29 Jesus answered and said to them, "
This is the work of God, that you believe in Him whom He sent."
[Jhn 6:29 NLT] 29 Jesus told them, "
This is the only work God wants from you: Believe in the one he has sent."
[Jhn 6:29 CSB] 29 Jesus replied, "
This is the work of God -- that you believe in the one he has sent."
[Jhn 6:29 NASB20] 29 Jesus answered and said to them, "
This is the work of God, that you believe in Him whom He has sent."
[Jhn 6:29 NASB95] 29 Jesus answered and said to them, "
This is the work of God, that you believe in Him whom He has sent."
[Jhn 6:29 LSB] 29 Jesus answered and said to them, "
This is the work of God, that you believe in Him whom He has sent."
[Jhn 6:29 NET] 29 Jesus replied, "
This is the deed God requires - to believe in the one whom he sent."
[Jhn 6:29 RSV] 29 Jesus answered them, "
This is the work of God, that you believe in him whom he has sent."
[Jhn 6:29 ASV] 29 Jesus answered and said unto them,
This is the work of God, that ye believe on him whom he hath sent.
[Jhn 6:29 YLT] 29 Jesus answered and said to them, '
This is the work of God, that ye may believe in him whom He did send.'
[Jhn 6:29 DBY] 29 Jesus answered and said to them,
This is the work of God, that ye believe on him whom he has sent.
[Jhn 6:29 WEB] 29 Jesus answered and said to them,
This is the work of God, that ye believe on him whom he hath sent.
[Jhn 6:29 HNV] 29 Yeshua answered them, "
This is the work of God, that you believe in him whom he has sent."
[Jhn 6:29 BBE] 29 Jesus, answering, said to them,
This is to do the work of God: to have faith in him whom God has sent.
[Jhn 6:29 AMP] 29 Jesus answered, "
This is the work of God: that you believe [adhere to, trust in, rely on, and have faith] in the One whom He has sent."
Just so that I am clear about what you're saying, my question is this: is it your contention that the above versions were translated incorrectly, and the way you've translated it is actually the correct one to use - and that the biblical scholars who did those translations were wrong or left something out? If so, would you mind sharing what your background in Greek is so that I can understand better where you're coming from?
Thanks,
Roger