We must always come back to what faith truly is, resisting the tendency to turn it into its opposite. Faith is looking trustingly to Christ rather than ourselves. Yet as soon as I begin to self-contemplate and consider the relative strength of my faith, I have aborted faith itself! Assessing what we bring to the table is the opposite of faith--and this includes assessing the strength of our faith. We assess the strength of Christ, period. As as we do so, that is faith.
I was reminded of this a few days ago by Schlatter. At age 85 in 1937, in the last of over 440 written publications, as Germany was sliding into moral chaos, Schlatter wrote:
We . . . must not attain righteousness by viewing our faith as a particularly meritorious type of conduct, as though through our faith we could persuade God to acquit us and to take us into his kingdom. The effective power of faith does not attach to the inner procedure that takes place in us when Jesus' Word makes us believe. Faith rather is rendered effective through the One in whom we believe, because he gives us everything he promises us.
--Adolf Schlatter, Do We Know Jesus? (trans. Koestenberger and Yarbrough; Kregel 2005), 109