You asked about the possibility of avoiding sin, and I showed you. But the last verse that I quoted in 2 Peter explains how by works the faithful “make sure their election”. Election is salvation, — that’s who the elect are.
Election and salvation are not the same.
What makes sure our salvation is believing in Christ’s shed blood on the cross for our sins. Someone could never do one “good deed” and still be in heaven upon death. Sadly, they would have very little as far as rewards at the Judgment Seat of Christ.