The best way to conquer evil is to do righteousness, serving God and mankind. Sins of omission are every bit as devastating as sins of commission.
To be made clean only prepares us for producing fruit. If we stand still, simply resting on our justification, the dark forces will pull us backwards.
Jesus' triumphal entry into Jerusalem fulfilled prophecies. The crowds welcoming Jesus were actually choosing the Paschal Lamb of God on Abib/Nisan 10.
We earn God's favor by obedience; there is a direct tie between submission to His will and His favor. The more one submits, the more favor and grace accrues.
The Parable of the Talents teaches the need for diligence in using the gifts of God. God expects us to use our talents to His glory and in the service of others.
Solomon's statement that all of life is vanity is only true if one is not privy to God's ultimate purpose for mankind. Paul describes what God is doing.
Ecclesiastes is perhaps the most practical book in the Old Testament, providing overviews of life-guiding advice, essentially a roadmap through the maze.
When the fifth commandment is neglected, respect for leadership and authority erodes, lowering quality of life, and ultimately, length of life too.