It’s childish.
“I love God so I can go to heaven!” That’s like my four year old telling me that he’ll love me if I’ll just buy him that shiny new toy.
“I do the right thing so I can go to heaven.” Yeah, and I’ll return your lost dog if you give me a reward. Shouldn’t you do the right thing because it’s the right thing, reward or not?
“I won’t hurt people so I can go to heaven.” Some kind of babyish extortion, that you won’t hurt God’s beloved children if God will let you through the pearly gates.
“I’ll put up with all the crap dished out to me because my reward is on the other side.” That’s a good way to waste a life. Don’t fight injustice, don’t face your problems, don’t tackle challenges or stand up to oppressors or otherwise put yourself in an inconvenient position. Just wait around like a passive tot for Mommy and Daddy to make it all better “later.”
And what if after you die God meets you on the other side and says, “Hey, I’ve got another somewhat challenging adventure I need you to go on…” Are you going to stomp your feet and wail, “But you PROMISED!!!”
Can we grow up, engage in the task at hand and quit jonesing for an eternal reward? Adults shouldn’t need such juvenile motivation.