Do we have a duty to believe? Is there some inherent merit in faith?
We are commanded to believe, so this would also be a duty, that seems quite clear:
Mark 1:15 “The time has come,” he said. “The kingdom of God is near. Repent and believe the good news!”
And faith is, in fact, commended:
Hebrews 11:1-2 Now faith is being sure of what we hope for and certain of what we do not see. This is what the ancients were commended for.
Here is one example:
Hebrews 11:11 By faith Abraham, even though he was past age–and Sarah herself was barren–was enabled to become a father because he considered him faithful who had made the promise.
And here is what Paul thinks of this example:
Romans 4:3 What does the Scripture say? “Abraham believed God, and it was credited to him as righteousness.”
So this faith was saving faith, and it was commended, and therefore virtuous.
If Rom. 4:3 does not describe Abraham’s conversion, then we have to ask why this act of faith was not the first time he had been considered righteous. Paul seems to imply clearly that this act of faith resulting in God considering him righteous:
Romans 4:21-22 being fully persuaded that God had power to do what he had promised. This is why “it was credited to him as righteousness.”
And then we have this verse showing what “it” refers to:
Romans 4:3 For what does the Scripture say? “And Abraham believed God, and it was reckoned to him as righteousness.”
“It” must refer to “Abraham believed God,” in this instance, most probably, and thus this would be the moment of his conversion, when he was first accounted righteous, and similarly, with us:
Galatians 3:6-7 Consider Abraham: “He believed God, and it was credited to him as righteousness.” Understand, then, that those who believe are children of Abraham.
Linking Rom. 4:3 with our believing, at the moment of conversion, it would seem to me, and thus God must do this entirely, if it is commendable.
Also, faith is of no value without love, and “love comes from God” (1 Jn. 4:7). So then sincere faith must also be accompanied by love such as God has, and how can this be present in an unbeliever, without the Holy Spirit (Rom. 8:9, Jude 1:19), how can there be love, without the Spirit of love (Rom. 5:5, Gal. 5:22)?
So if faith is accompanied by the love of God, bound up in the love of God (“faith working through love” is what counts, Gal. 5:6) then indeed it has merit, it is bound up in the first and second commands to love God and our neighbor, which also would make faith part of this duty.