When Jesus spoke that to His disciples, He was referring specifically to the 'works of righteousness which God has ordained that we should walk in'. It is specifically to Christians that we can accomplish nothing in our working outward of own salvation that fails without Him, His Spirit in us allowed to 'weed the garden'.
Too many men and women believe they are accomplishing much striving to obtain eternal life by fealty to sacraments and rituals without aiming their will to rely on Only Jesus Alone for their deliverance. Islam is a strong example of that ... not referring to the terrorist embedded in Islam. Sadly, Catholicism is another example of that same stumbling.
On the contrary, Sacraments are invitations to become ever closer to Christ. To live in Him, to experience Him living in us.
That's why He said, for instance,
" Truly, truly, I tell you, unless you eat the flesh and drink the blood of the Son of Man, you have no life in you.
Whoever eats My flesh and drinks My blood has eternal life, and I will raise him up at the last day.
For My flesh is real food, and My blood is real drink."
We've discussed this before, and there's no need for you to repeat your arguments to the contrary: I can find them on Google,or enter your username on the FR search function.
Perhaps you don't think that is actually real or true: but otherwise, it's hard to explain why He said it. When He was challenged on it in John 6, He kept repeating it with all the greater vehemence. People walked away, and He just said it again.
Realism: the flesh (OUR own carnal meat-headedness) avails nothing in explaining this. HIS flesh avails everything.