Part I
If you “believe in Jesus” but believe you can’t do any sin and still end up in Heaven, you’re believing in yourself for salvation. (Because Jesus paid for all your sins.)
Salvation is not by our works.
If you “believe in Jesus” but still believe you have to do good things to go to Heaven, you’re believing in yourself for salvation. (Because Jesus is the righteousness of the believer.)
Does this mean you should do a lot of sins and no good works?
No.
It means that these things do not help get you into Heaven.
The greatest trick of Satan is to get people to admire Jesus, repent of their sins, and do good works—and end up in Hell in the end.
Jesus forgives all your sins past, present, and future, and Jesus’ righteousness is far better than all your paltry good works.
Do you believe in Jesus, or do you believe in ~you~ for salvation?
Part II
If you believe in Jesus ~alone~, you can know that:
you have eternal life,
you are completely forgiven,
you are declared not guilty of sins.
you are born again,
you are sealed by the Holy Spirit,
you are eternally and irrevocably saved,
you are eternally secure,
you will “never perish,”
you were crucified with Christ and risen with Christ,
you are seated in the heavenly places,
you are a citizen of Heaven,
your name is written in Heaven,
you were chosen in Christ before the foundation of the world, 
you are indwelled by the Holy Spirit,
and you are a child of God.
It is theoretically possible that you could continue in a sinful life; and you could quench the work of the Holy Spirit, but you would be fighting against the influence of the Holy Spirit to lead you to love and righteousness and God’s will.
Repenting of sins and doing good works are definitely not evidences of salvation because unbelievers can repent of their sins and alcoholics can stop drinking and Atheists can do good works and give to charity.
Repenting of sins and doing good works are what the Holy Spirit will lead you to do—but you must seek God and be a branch to the Divine Vine.
The greatest evidence of salvation is you knowing that you believe in Jesus.
And the fruit of the Spirit is love, joy, peace, patience, kindness, gentleness, goodness, faithfulness, and self-control.
We are not under the Law, we are under grace.
Believers can live in the love of God as new people in Christ.
Curtis Smale
Grace, Insight, and Art 