according to protestantism or evangelism the salvation is only by grace or accepting

then only praying and stuff like that that you will be saved then a thief because he believed in Jesus it will be go to heaven ? also anybody because they believe in Jesus

Yes. In heaven there will be many liars and thieves.

All must repent and be forgiven.

Yep anybody. Jesus died for all people's sins. But that doesn't mean it is a "get out of jail free" card. You can only really accept him if you have a change of heart and sincerely repent. With the new life in Christ you will be unhappy when you make sinful choices in the future. You won't be perfect, but you will try not to continue in sin. For a wonderful understanding of this concept please read "Satan is Alive and Well on Planet Earth" by Hal Lindsey.

It's a clear case of both:

Salvation is entirely of grace. Jesus Christ is God's gift of Grace. But in order for a gift to be a gift, it must be both freely given and freely received. God freely gives - have you freely received his gift?

1Cr 2:12 Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God.

Jhn 17:8 For I have given unto them the words which thou gave st me; and they have received [them], and have known surely that I came out from thee, and they have believed that thou didst send me.

Mat 10:8 Heal the sick, cleanse the lepers, raise the dead, cast out devils: freely ye have received, freely give.

1Cr 2:12 Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God.