You ask, will the heterodox be saved... Why do you worry about them? They have a Saviour Who desires the salvation of every human being. He will take care of them. You and I should not be burdened with such a concern. Study yourself and your own sins... I will tell you one thing, however: should you, being Orthodox and possessing the Truth in its fullness, betray Orthodoxy, and enter a different faith, you will lose your soul forever.