For some, this is a tricky subject, but we find the idea of "according to your faith" or similar in several places:
- Matt 9:29 - Then He touched their eyes, saying, "According to your faith be it to you."
- Rom 12:3 - For by the grace given me I say to every one of you: Do not think of yourself more highly than you ought, but think of yourself with sober judgment, according to the measure of faith God has given you.
- Rom 12:6 - And we are having different gifts according to the grace having been given to us: if prophecy, according to the proportion of the faith;
Thus, Rom 12:6 is explained by v3 - our faith is a gift of God as well (where else could it come from??) That is, Paul is encouraging each person to exercise their spiritual gifts, especially prophecy, according to measure imparted by God and no less.
Barnes notes this:
According to the grace - That is, the favor, the mercy that is bestowed on us. As all that we have is a matter of grace, it should
keep us from pride; and it should make us willing to occupy our
appropriate place in the church. True honor consists not in splendid
endowments, or great wealth and function. It consists in rightly
discharging the duties which God requires of us in our appropriate
sphere. If all people held their talents as the gift of God; if all
would find and occupy in society the place for which God designed
them, it would prevent no small part of the uneasiness, the
restlessness, the ambition, and misery of the world.
When commenting on Rom 12:3, the Pulpit commentary says this:
the measure of faith Cp. Ephesians 4:7, where (see Romans 12:11) the context is similar to this. There, however, the word “grace” is
used where “faith” is used here; and “faith” here is not quite easy of
explanation. In this Epistle the special aspect of faith (trust in God
and His word) as justifying has been consistently in view, rather than
its aspect (Hebrews 11:1) as laying hold upon invisible realities in
general. Here, therefore, it seems best to seek for a reference as
consistent as possible with that of the rest of the Epistle, and one
also which shall harmonize with the phrase in Romans 12:6 below; q.v.
We explain the present passage then as follows:—“Faith” here means
specially acceptance of Christ, revealed as the Propitiation: but that
acceptance is also, ipso facto, the entrance on bondservice to God,
(see e.g. Romans 6:18 :) therefore the gift of faith is here mentioned
as involving the idea of the allotment of consequent duties and
functions also to the various believers with their various capacities.
Faith, in the Divine plan, is the grand qualification for service,
(because it is the appointed instrument of reconciliation;) and it is
therefore the sphere, so to speak, in which all true service is to be
Note one more verse in Eph 4:7 -
Now to each one of us grace has been given according to the measure of
the gift of Christ.
Thus, in this context, the gifts of the Spirit, the grace and faith of God are imparted according to the will of God.