TxNVSue2023: No one is going to buy their way to the new world with extra activity or donations.
I agree with your premise. A lack of sincerity will not fool a god who knows our thoughts and intentions. For a believer, this truth should be paramount and ever-present and should guide their every living moment. But I would gather that there are very few people who live this kind of a life, even when they are devout believers in god and in their religious doctrines. It is no accident that "the end is near" messages have been almost constant in the centuries since the birth of Christianity. Perhaps we were created to lack urgency?
By and large, most people --including many devout believers-- live their daily lives with little more than a passing recognition of this cosmic responsibility, despite knowing that a very great or very awful outcome awaits. I think fewer and fewer people are convinced that anything will happen within their lifetimes, if at all. For the believer, this should be moot-- if god will bring about a specific future, it will happen. But I can't help but feel as if more and more, people are living their lives as if nothing is going to happen. And for all of them to date, this attitude has been justified.
An eternal god can exercise eternal patience. A very time-limited human race cannot. At some point, god has to show up, or the human race might realize that he's not something they need to concern themselves with.