“Their mouth is full of cursing and bitterness.”

Now we know that whatever the Law [of Moses] says, it speaks to those who are under the Law, so that [the excuses of] every mouth may be silenced [from protesting] and that all the world may be held accountable to God [and subject to His judgment].

For with the heart a person believes [in Christ as Savior] resulting in his justification [that is, being made righteous—being freed of the guilt of sin and made acceptable to God]; and with the mouth he acknowledges and confesses [his faith openly], resulting in and confirming [his] salvation.