The two "with" prepositions in this verse are not the common word translated as "with." Instead, it is a preposition that means "by the side of," from with we get the word "parallel." The sense is that there are two sides, men and God and that we align with one or the other.
This is a rare time when Jesus does not use an article with the word translated as "God."
The word "saved" did not have the same meaning in Jesus's time and to the apostles as it does in a religious sense now, but it did have the same general sense of "rescue." We talk today about medicine saving lives, good habits saving lives, a rescue from a burning building saving lives, or spending more money saving lives. But we mean only extending life for a limited time. Everyone who has been born on earth has or will die an earthly death among men. The only way our lives are rescued is by being enfolded in the eternal.
Christ's Words in Matthew as a Guide to 40 Days of Prayer.