Amen. That single, factual light-bulb recognition unites every Reformed believer who knows all of salvation, but most especially its inception and completion, is by the will of God alone.
It's either/or; black/white; God ordained/man accomplished.
Either God chose His elect from before the foundation of the world based upon NOTHING in the creature, but according to His sovereign will alone (all men being equally fallen and unable to perform anything God-pleasing), or man has some part in the acquisition of his salvation (which incorrectly presupposes some men are better, smarter, more pious than other men because they "choose" correctly.)
"Jesus answered and said to them, "This is the work of God, that you believe in Him whom He sent." -- John 6:29
Either/or.
Since so many of us started out as Arminians (the cultural bias of modern man), we've experienced firsthand this gradual, inevitable progression from Arminian to Reformed, from man to God, from 50/50 to 0/100, from me to only Him, from possibility to predestiny, from hope to true assurance.
That's my tag-line...nice to see it in bold red!!