Nay, we establish the law (alla nomon istanomen). Present indicative active of late verb istanw from isthmi. This Paul hinted at in verse Romans 21 . How he will show in chapter 4 how Abraham himself is an example of faith and in his life illustrates the very point just made. Besides, apart from Christ and the help of the Holy Spirit no one can keep God's law. The Mosaic law is only workable by faith in Christ.