I did quote the context verse, it is at the start of the chapter. Maybe I should have quoted more. Apologies for that.
Eph.2:1-10
And you He made alive, who were dead in trespasses and sins, 2 in which you once walked according to the course of this world, according to the prince of the power of the air, the spirit who now works in the sons of disobedience, 3among whom also we all once conducted ourselves in the lusts of our flesh, fulfilling the desires of the flesh and of the mind, and were by nature children of wrath, just as the others.
4But God, who is rich in mercy, because of His great love with which He loved us, 5even when we were dead in trespasses, made us alive together with Christ (by grace you have been saved), 6and raised us up together, and made us sit together in the heavenly places in Christ Jesus, 7that in the ages to come He might show the exceeding riches of His grace in His kindness toward us in Christ Jesus. 8For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, 9not of works, lest anyone should boast. 10For we are His workmanship, created in Christ Jesus for good works, which God prepared beforehand that we should walk in them.
We can see from verse one the context is regeneration, being made alive in Christ and He did this for the purpose of good works which will be produced if we continue to walk in the faith we have been given. We are not made alive based on those good works though, so why think we remain alive based on anything we do?
Being made alive in Christ by grace through faith is never going to change, it remains true at every point in time. We had no faith until that moment we were made alive. I don't understand why you think our will can undo God's work? How can He show the exceeding riches of His grace if our will can disband what the Lord has done?