I have been trying to do Christianity exactly by the book and it has worn me out. Does God accept an ordinary, simple faith like mine?

“LORD, my heart is not haughty, nor mine eyes lofty: neither do I exercise myself in great matters, or in things too high for me. Surely I have behaved and quieted myself, as a child that is weaned of his mother: my soul is even as a weaned child.”

This is one of the shortest psalms, written by David as a song for pilgrims walking up to Jerusalem. He describes deliberately declining matters too high for him and settling like a weaned child against its mother. A weaned child is no longer there for what it can get, only to be near. That is a picture of faith without striving, and David offers it as maturity rather than laziness.

“Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh?”

The Galatians had received the gospel gladly and then started adding requirements in order to secure their standing. Paul's question is almost incredulous: having begun in the Spirit, are you now being perfected by your own effort? He is not arguing against obedience. He is arguing against the instinct to finish by performance what was started by grace, which is precisely the perfectionist's instinct.