If you could get to heaven by just being good enough, Jesus died for nothing.
If Jesus died for our sins on the cross, and we continue to sin, Jesus died for nothing.
For it is by grace you have been saved, through faith—and this not from yourselves, it is the gift of God— not by works, so that no one can boast. For we are God's workmanship, created in Christ Jesus to do good works, which God prepared in advance for us to do. Eph 2:8-10
(God's word says it better than me :)