Grace and Truth
It is easy to underestimate both the generous kindness of God and His unyielding commitment to truth. I love the eloquence and clarity of this description of both sides of God’s character in dealing with His children:
Our Heavenly Father is more liberal in his views, and boundless in his mercies and blessings, than we are ready to believe or receive, and, at the same time, is more terrible to the workers of iniquity, more awful in the executions of his punishments, and more ready to detect every false way than we are apt to suppose him to be.
On the one hand, virtually all human beings are destined for eternal glories that surpass all mortal understanding. When it comes to His children here on earth, He “saves all the works of His hands” — apparently with vanishingly few exceptions. Each of us is a child of God with a permanent place in His household, which indeed has “many mansions.”
On the other hand, this is a graded universalism. A large estate exhibits diversity, with allowance for servants, stewards, and sons. Nobody will be placed in circumstances and endowed with eternal powers which they are not well prepared to handle upon principles of righteousness. And for many, “hell” is apt label for the wrenching encounters with bedrock truths of the universe they will experience by way of preparation for the degree of glory they will be able to abide and enjoy.
So while a place in the network that is God’s household is essentially unconditionally guaranteed, the nature of our presence there — in particular, whether we become a node in that network that spawns a new, infinitely expanding subnetwork, an infinite family of our own, as not just servants or stewards but as sons and daughters, heirs to our heavenly parents — depends upon the deepest desires of our own hearts, manifest in our response to the extravagant grace and strict truth of God, our Heavenly Father.
Note: The statement quoted in the second paragraph above is attributed to the prophet Joseph Smith, but its provenance is contested.