Those who's righteousness is by human willpower are the ones in true danger because they don't understand their need for mercy.
There is of course, a middle ground.
I don't believe we can achieve righteousness without Jesus, we neither have the capacity or desire to do it without Jesus/Holy Spirit's help.
On the other hand, we still have the free will to reject this help. So from that perspective it takes effort on our part.
There are some who say Jesus wants all the credit 100%, and if we say we are responsible for even 1% then we are taking away from His glory.
I disagree. None of us will be saved without Jesus. From that perspective He gets credit for 100% of the people who are saved.
But if we say Jesus is in total control of our salvation and actions, then we also have to say He is controlling the sinful actions that we still do sometimes.
I don't think He wants credit for that.
If we take the classic passages about the tree that was given 3 years to start bearing fruit (but if it doesn't cut it down).
Or the 10 virgins (5 of which were foolish and ran out of oil)
Or the servant (who was kicked out of the masters house) who buried his talents in the sand while the other two went out and invested their talents.
Or those who strive to enter the narrow gate but are unable, they thought that simply by eating in his presence and listening to His teaching they would be saved.
Or even those who claimed to do miracles and cast out demons in His name but were unable to enter the kingdom of God.
Who failed in all the instances above? Was it Jesus? Or was it humans who made bad choices and thought Jesus was going to take care of it all 100% ?
We are responsible for our actions. We are responsible for our sin. Yes there is mercy and grace. Yes there is forgiveness (for those who repent).
But should we sin more just so grace can increase? The Bible mentions those who turn the grace of Christ into a license to sin.
Grace is there for when we make mistakes, grace is not there so we can do and live however we want.
Believing in Jesus means believing in His words, His actions, His teachings, and following them.
When Jesus says "Well done, good and faithful servant" is He talking to Himself? ..or Us?