He (Avram) believed, and he was declared righteous. ( Genesis15:6) When I read this verse in The Complete Word Study Old Testament I saw that the original word for 'believe' is pronounced 'amen'. Is this amen the same as Amen that we say in church? It looks like this amen in Genesis 15:6 is a prime root, and it means to build up or support. In Psalms 89:52 we read "Blessed be the LORD forever more. Amen, and Amen." And this amen (#543)came from Avram's amen (#539). So they are related!
Abram 'amen'-ed, and God declared him righteous.