Is it permissible for me to bind a Gospel for a Christian in the same way the Qur’an is bound, and will I be held accountable for that, or for the money I will receive for this service?

You are not permitted to do that, as it involves affirming falsehood, embellishing it, and promoting it. This is no different from the ruling on writing, printing, and selling such books, which is explicitly prohibited. Al-Nawawi said: "It is not permissible to sell books of disbelief, because there is no lawful benefit in them; rather, they must be destroyed." Al-Ghamrawi said: "It is not permissible to sell books of disbelief — such as the Gospel — nor books of magic and astrology; rather, they must be destroyed." This sale is forbidden even if the buyer is a Christian, because it involves affirming their falsehood and assisting them in it. Al-Dasuqi said: "It is forbidden to sell the Torah and the Gospel to them, because they have been altered; this involves assisting them in their delusion."