Therefore, my beloved, as you have always obeyed, so now, not only as in my presence but much more in my absence, work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure. (Php 2:12).There's a good reason to be afraid - because our God is a God of justice and wrath, a God who will not let the unrepentant and unjust go unpunished - either in this life, or whatever comes after. While the Law testifies to the perfection of God and so convict us of our sin, it will be God Himself who will enforce it and render judgment. Nothing in all of creation can escape, and on the day of judgment, you will have to give account for all the words you speak:
I tell you, on the day of judgment people will give account for every careless word they speak, for by your words you will be justified, and by your words you will be condemned.” Mt 12:36and
And no creature is hidden from his sight, but all are naked and exposed to the eyes of him to whom we must give account. Heb 4:13
Consider the parable of the unforgiving servant - he's forgiven an un-imaginable debt, then goes out and shakes down his fellow servant for a trifle, and when the king hears about it, has him thrown in debtor's prison until the debt's completely paid.
And that's where people usually stop - right before the punchline.
So also my heavenly Father will do to every one of you, if you do not forgive your brother from your heart.” Mt 18:35When the Spirit opened my eyes to that particular passage, it was like a 2x4 upside the head. I kept on wondering why I'd never heard that before.
However, serious as all this is, there is still hope - to return to the passage I'd originally cited:
...for it is God who works in you, both to will and to work for his good pleasure. (Phillipians 2:12)We as believers have not been left alone, God's right there, in each and every one us, helping us along to do what we cannot do on our power. So just as we should be scared out of our wits by the implications of what we're facing at Judgment, we can take even greater comfort and joy in the promised saving work Christ has done - and continues to do - in us. As it is written:
Therefore I tell you, her sins, which are many, are forgiven—for she loved much. But he who is forgiven little, loves little.” Lk 7:47
All citations from The Holy Bible : English standard version. 2001 Wheaton: Standard Bible Society.