It’s rather presumptuous for some to call things legalism which are spelled out in Scripture.
When does one know if they've 'done enough'?
Only God knows how much is enough. All one can do is respond to His Grace and bear fruit accordingly, and approach God as the remorseful tax collector did—not as the Pharisee did.
I’ve seen some people who are convinced that they’re saved, yet cheat people out of money owed and do things that certainly don’t give witness to Christ. My point was that there are examples in the Gospel where Jesus teaches us to act in faith (parable of the Good Samaritan; the rich follower whom Jesus told to sell all of his possessions and give the money to the poor).