Unwarranted confidence in human ability is a product of fallen human nature ... God's grace in Christ is not merely necessary but is the sole efficient cause of salvation. We confess that human beings are born spiritually dead and are incapable even of cooperating with regenerating grace. We reaffirm that in salvation we are rescued from God's wrath by his grace alone. It is the supernatural work of the Holy Spirit that brings us to Christ by releasing us from our bondage to sin and raising us from spiritual death to spiritual life. We deny that salvation is in any sense a human work. Human methods, techniques or strategies by themselves cannot accomplish this transformation. Faith is not produced by our unregenerated human nature. - Cambridge Declaration
It is not confidence in human ability to believe a person who lives in the true grace of the Bible must see much victory over sin in their life. It is confidence in the Gospel of grace as written in the NT and the power of God to transform a life that loves and trusts in his son to change them, and relies on the Holy Spirit to sanctify them
And the person who truly loves God with all their heart wants none of the credit for the victory achieved in their life, and wishes God to be given all the glory for what has been done in them, they seek no glory of their own, they seek no recognition from man, they love God far too much for that.
But to preach a grace that does not have to see tremendous victory over sin in the individuals life is to preachy a false grace, it is not speaking of the grace of the Bible, just being selective with what you quote of God's word. A grace thast does not result in great change in an indivuduals life is not the grace of the Bible, the Bible is plain on that