The beginning of this part of Psalm 73 is one that I have seen translated as a question, and I think it is perhaps more accurate as such, but the overall point remains the same:
13 All in vain have I kept my heart clean
and washed my hands in innocence.
14 For all the day long I have been stricken,
and chastened every morning.
15 If I had said, “I will speak thus,”
I would have been untrue to the generation of thy children.
16 But when I thought how to understand this,
it seemed to me a wearisome task,
17 until I went into the sanctuary of God;
then I perceived their end.
When we find ourselves surrounded by evil it is only natural that we will question our adherence to God’s laws. At least, I find myself asking this question not infrequently. Fortunately, our savior explained to us why we should keep our hearts clean:
Blessed are the pure in heart, for they shall see God.
What does Jesus mean by this? He means that we shall see and know God, and He shall see and know us. For what else matters but that on the Day of Judgment?
21 “Not every one who says to me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of my Father who is in heaven. 22 On that day many will say to me, ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’ 23 And then will I declare to them, ‘I never knew you; depart from me, you evildoers.’