Yes, I'm serious. Why did God count Abrahams' faith as righteousness to him, when according to Calvanists, he had nothing to do with it? Go ahead.
As brightfame52 alluded to, everyone, including Abraham are saved in the same way.
I think what is not obvious in the verse is that there are in a sense two faiths at work, not one:
the faith of Christ and the faith given to Abraham. If we try to interpret the verse as being solely a reference to a faith that was self-generated by Abraham, the pieces won't fit.
To understand
Gen 15:6 we cannot just look at it in isolation and assume what the pieces mean, but have to factor in other verses which provide a complete picture. In
Rom 4:9 we see that "faith was reckoned to Abraham for righteousness". Faith was "reckoned" to Abraham, meaning calculated or imputed as though it was his when it wasn't. Who's faith? Christ's faith. This because in Phl 3:9 and Rom 4:13, we see that righteousness is "the faith of Christ". So, a faith that is not of Christ has no righteousness of itself for it to reckon righteousness. For Abraham, in order to have righteousness, it had to be of Christ's faith not his faith: righteousness is of His faith (Rom 4:13, Phl 3:9).
In
Rom 3:22, we can see that unto those who believe, their belief comes from and by, the faith of Christ.
In
Rom 4:5 we can see that "his faith", Christ's faith, is counted for righteousness. Again, because Christ's faith is righteousness, and no other faith can claim it
So, if Abraham had faith reckoned to him for righteousness (Rom 4:9), it was by Christ.
Now, since God counted Abraham's faith as righteousness, and righteousness can only come by Christ,
then that Abraham believed, had to be the result of Christ, not Abraham and Abraham gets no credit for it.
Otherwise, God could not rightfully attribute any righteousness to it; that is, a man-made faith cannot provide righteousness because man's faith has no righteousness (see Phl 3.9) - any righteousness produced by man can only be of the law, and the law only brings judgment, not righteousness: a faith without righteousness cannot give righteousness.
So, to summarize, everything of Gen 15:6, came to Abraham as a gift from God through Christ, as it does with all who become saved.
There's a lot more but this should suffice for now.
[
Gen 15:6 KJV] 6 And he believed in the LORD; and he counted it to him
for righteousness.
[
Rom 3:22 KJV] 22
Even the righteousness of God [which is] by faith of Jesus Christ unto all and upon all them that believe: for there is no difference:
[
Rom 4:3 KJV] 3 For what saith the scripture? Abraham believed God, and it was counted unto him for righteousness.
[
Rom 4:5 KJV] 5 But to him that worketh not, but believeth on him that justifieth the ungodly,
his faith is counted for righteousness.
[
Rom 4:13 KJV] 13 For the promise, that he should be the heir of the world, [was] not to Abraham, or to his seed, through the law,
but through the righteousness of faith.
[
Rom 4:9 KJV] 9 [Cometh] this blessedness then upon the circumcision [only], or upon the uncircumcision also? for we say that
faith was reckoned to Abraham for righteousness.
[Phl 3:9 KJV] 9 And be found in him,
not having mine own righteousness, which is of the law, but
that which is through the faith of Christ, the righteousness which is of God by faith:
[Rom 4:13 KJV] 13 For the promise, that he should be the heir of the world, [was] not to Abraham, or to his seed, through the law,
but through the righteousness of faith.