Many readers of Scripture have no concept of the evolution of faith contained in those writings. They simply presume the faith motivating the first chapters of Genesis is the same faith motivating the last chapters of Revelation. Nothing could be further from reality. Biblical faith constantly evolves the more we understand our experiences with God and God working in our lives.
In the beginning of the biblical period - tenth or eleventh century BCE - for instance, our sacred authors presumed Yahweh was simply one God among many gods. Only in the sixth century BCE, during the Babylonian Exile, do Jews begin to understand that Yahweh is the one and only God. In a parallel way, until about a hundred years before Jesus' birth, our inspired writers took for granted this life is the only life we'll ever experience. Everything began with our birth and ended with our death.
As a Pharisee, the historical Jesus was a believer in that new-fangled notion of an afterlife. He presumed those who formed a relationship with Yahweh in this life, would continue that relationship with Yahweh in a life beyond our physical deaths.
Not all Jews of Jesus' day and age accepted such a liberal theology, as we hear in today's gospel pericope. "Some Sadducees, those who deny there is a resurrection came forward . . . ." They present Jesus with what could only be called a "smutty" example of the impossibility of an afterlife: a woman involved in multiple marriages. "At the resurrection," they demand to know, "whose wife will she be?"
Jesus' major argument for the woman's seven husbands not being an insurmountable eternal life dilemma revolves around what we're going to experience in that eternal life. It's not going to be just a simple Groundhog's Day rerun of this life. Those who continue their relationship with God into the next life are going to find themselves in a whole new existence. Just as our outside the womb existence is dramatically different from our fetal existence, so heaven will be dramatically different from this earthly existence. The Sadducees arguments against eternity are based on a false concept of eternity.
Of course, none of us, except for being confident we'll have a relationship with God, is certain about what eternity holds for us. The seven brothers in our II Maccabees reading are confident they'll continue to live after their martyrdom but no one says anything about the form that life will take. They're simply relying on" ... the hope God gives of being raised up by him ...."
Perhaps that's why the author of II Thessalonians encourages his readers to do the only thing which will determine whether they'll be part of a heavenly afterlife, or be left out in the cold (or heat). "May the Lord direct your hearts to the love of God and to the endurance of Christ." After all, God". . . loves us ... and encourages (our) hearts and strengthens them in every good deed and word."
Most of us, like the writer's mentor Paul, or the seven brothers, or Jesus, aren't going to experience a martyr's death - the most certain way of getting into heaven. We're going to have to go through a natural lifetime of building relationships with God and those around us. And as anyone who works at building relationships knows, we're never certain where those relationships are ultimately going to take us. We simply have faith that not building relationships results in a hell of an existence, something which, no matter how many times we've been married, we'd like to avoid.