Of course God is too great to be summed up in a single word or phrase. But in Psalm 136, the writer clearly highlights one of God's primary characteristics. This seems to be one quality that God wants us to notice and remember.
His love endures forever.
All 26 verses in this Psalm end with this refrain. When we thank him, when we see his creation, when we experience his protection, when we witness his justice--in all these circumstances we need to remember that his love endures forever.
God has many other attributes, but we must keep on remembering that his love endures forever. Not his justice, his power, his might, or even his glory--his enduring LOVE we must remember. Obviously other places in the scripture highlight God's other attributes. But here the psalmist drives home God's love.
This word for love also means loving-kindness or covenant love. We must never forget God's love for us. I need to remember that every day. That helps me experience his love and live his love.