There is no passage of time between faith and justification. Both occur simultaneously. There is also no such thing as a faith which starts off as dead. That is not what Sola Fide means. Therefore, this conclusion is built on a straw man.
"(2) Justification must be what bestows love, and this seems confirmed by Scripture (e.g. Romans 5:5), and thus the Protestant can no longer say justification is purely forensic, but rather infuses divine gifts into the soul.
The Holy Spirit pours the love of God into our hearts, which is related to our justification. But this act of the Spirit is not to be equated or conflated with the instance of justification. Grace and faith do have an effect on our love.
Forensic justification causes things which are not forensic in nature to happen. We obtain peace with God by faith, which includes assurance of salvation and the freedom to pursue holiness in gratitude for what God has done for us. These blessings have a consequential relationship to justification by faith alone.
The phrase "faith working through love" in Galatians 5:6 implies the existence of a faith that is ongoing. Belief in Sola Fide is not a denial of this. The relationship of God to the unbelieving world is that of a judge to a convict, whereas our relationship to Him is that of a father to a son.
"(3) Dead faith prior to justification becomes living faith after justification by the addition of love to faith, and herein is the essence of a justified believer. This would mean it isn't Christ's Imputed Righteousness that makes all the difference, but rather the presence/absence of love, and thus suggests your justification (salvation) hinges upon what you do with that love. This is why texts like Revelation 21:8 list "unbelief" as one of the many sins that can damn a person, because it's possible to have faith and be damned by other grave sins."
The presence of love serves as evidence of a regenerate heart. In addition, the reason that "unbelief" is listed as one of several damnable sins in Revelation 21:8 is that it is the opposite of belief. Faith is the instrument by which God justifies us. Thus, that passage is perfectly consistent with the doctrine of Sola Fide.
"Given the above, when Paul says we are "justified by faith," he isn't saying we are "eternally saved by faith," rather he's saying that we receive God's love within us by believing in the Gospel, and that this is just the beginning of our salvation (Rom 13:8-14; Gal 5:13-14)."
We would agree with the above comments. The moment of conversion is simply the beginning of our salvation. Justification is an aspect, but not the entirety of the process. What we would argue against is the idea of man earning the grace of God on the basis of good works.