Doesn't it sound like in the passages the you can harden your heart?
That's how I would interpret this.
How bout you?

1Let us therefore fear, lest, a promise being left us of entering into his rest, any of you should seem to come short of it.
2For unto us was the gospel preached, as well as unto them: but the word preached did not profit them, not being mixed with faith in them that heard it.
3For we which have believed do enter into rest, as he said, As I have sworn in my wrath, if they shall enter into my rest: although the works were finished from the foundation of the world.
4For he spake in a certain place of the seventh day on this wise, And God did rest the seventh day from all his works.
5And in this place again, If they shall enter into my rest.
6Seeing therefore it remaineth that some must enter therein, and they to whom it was first preached entered not in because of unbelief:
7Again, he limiteth a certain day, saying in David, To day, after so long a time; as it is said, To day if ye will hear his voice, harden not your hearts.
8For if Jesus had given them rest, then would he not afterward have spoken of another day.
9There remaineth therefore a rest to the people of God.
10For he that is entered into his rest, he also hath ceased from his own works, as God did from his.
11Let us labour therefore to enter into that rest, lest any man fall after the sa

Btw how do Calvinist evangelize?
Do they avoid saying anything that might require a response on mans part?
I'm just curious...

I don't dopey! What do u suggest I should do?

Tell me what would you say to someone who is troubled by the assurance of his salvation?

I'm a free willer and so I choose to have faith that Jesus is enough for the salvation of my soul. So I have faith that God saves me through Jesus Christs death. My faith is not a meritorious work but rather I choose to give God all the glory through my faith in his indescribable gift to me.