The scripture you gave me say what you claim only in your mind. Yes, Christ made the perfect sacrifice for our sins as 2 Corinthians quote explains, but no, the work and struggle goes on in each one of us individually, -- as Christ's talk of obeying the commandments, and carrying the yoke indicate, and as Paul's passages of fighting a battle, running a race, and fear and trembling teach.
The quote from Galatians does not teach assurance of individual salvation either, but it is also out of context since it refers to the works of Jewish law, such as dietetic law and circumcision. It says nothing about the works of love and charity, -- the virtues St. Paul held highly, as does the Church.
Sin, Confession, Eucharist is supposed to be an upward spiral to sainthood, -- "be perfect even as your Father in Heaven is perfect", but yes, for many, it becomes a cycle. Again, struggling in this cycle we hope for Christ's mercy as He knows our heart, and we hope that at the hour of our death Mary will pray for us even if we are not able to pray ourselves.
I asked this before, but didn't get a clear answer. It's a simple enough question.
Do you thank God you are not a reprobate?