To a modern reader, used to advertising and entertainment industries designed and geared to encourage hedonistic self-indulgence it sounds impossible. ‘No pressure there!’ we might feel like saying.
But I kind of see what He means.
There’s an Old Testament reference which says, ‘Above all else, guard your heart, for it is the wellspring of life.’ (Proverbs 4 v 23)
What we choose to welcome to our minds and dwell on can quickly become dominant and issue in actual words and actions! Our conversation or social interaction will often reflect the examples we’ve seen on TV or the net. People wear their hair, or curse and swear, or do sex and violence just like the idols they worship.
So maybe the Lord is wise after all in urging some self-discipline in our thinking!
Ultimately His sermon illustrates the uncomfortable truth, ‘All have sinned and fall short of the glory of God.’ (Romans 3 v23) All of us need to trust in Him as Saviour.
But how then can we deal with the unworthy thoughts and desires that still slip so easily into our conscious? The answer is to replace them quickly with more positive, reverent, honourable ones!
It comes down to what we allow to ‘dwell’ in us, what we invite in to make itself at home. It’s an old but excellent illustration that says we can’t stop the birds flying over or even landing on our head but we can prevent them nesting in our hair! Listen to what the Apostle Paul urges in Colossians 3 v 15-16:
‘Let the peace of Christ rule in your hearts, since as members of one body you were called to peace. And be thankful. Let the word of Christ dwell in you richly as you teach and admonish one another with all wisdom, and as you sing psalms, hymns and spiritual songs with gratitude in your hearts to God.’
If our hearts are filled with Christ’s peace, His word and wisdom, His Spirit and gratitude as a result, there will be little room left for less worthy items.