The 2nd Commandment does not apply to Icons

The most common objection that Protestants use against Catholics for venerating images of God and of the Saints is for Protestants to appeal to the Ten Commandments [1], specifically the 2nd Commandment (Exodus 20:4-5), which seems to plainly prohibit the making and venerating of any religious images. While this Biblical appeal might seem to be an open and shut, slam dunk against Catholicism, it actually contains a very problematic and erroneous approach to the Old Testament, which Saint Paul termed "Judaizing" in Greek (Gal 2:14). The reason why people fail to recognize this is because Protestantism was founded upon an erroneous, even Judaizing, approach to the Mosaic Law. I think it is worth bringing this up because too many times I've seen Catholics basically accept this very Protestant Judaizing premise behind their use of the 2nd Commandment, which is the real issue that needs to be exposed.

Before we can even look at the 2nd Commandment itself, the first critical thing to know is that the term "Law" for Paul absolutely means the Mosaic Law, whereas Protestants erroneously think "Law" means anything man is ever told to do (e.g. any work a man does). I have exposed this many times in past blog posts and in discussions, particularly how the Protestants failing to define "Law" properly is a main reason they completely misunderstand Paul and salvation. (e.g. HERE). 

To build in this point, it is critical to know that the Mosaic Law was also known as the Mosaic Covenant (what Christians call the "Old Covenant"), and that the Ten Commandments were literally the very core of the Old Covenant. I think Hebrews 9:5 captures this very well, practically calling these basic truths everyone already knows: 

1 Now even the first covenant had regulations for worship and an earthly place of holiness. 2 For a tent was prepared, the first section, in which were the lampstand and the table and the bread of the Presence. It is called the Holy Place. 3 Behind the second curtain was a second section called the Most Holy Place, 4 having the golden altar of incense and the ark of the covenant covered on all sides with gold, in which was a golden urn holding the manna, and Aaron's staff that budded, and the tablets of the covenant. 5 Above it were the cherubim of glory overshadowing the mercy seat. 

Note how the Ten Commandments were called "the tablets of the covenant" and thus were put inside the Ark of the Covenant. Knowing this basic theological truth is critical. I show this plainly elsewhere as well (e.g. HERE with Deut 9:9). Once a person recognizes this solid link between the Mosaic Law and Ten Commandments as the Old Covenant, it sets us up to be forced to admit that when the Old Covenant was done away with at the death of Christ on the Cross, that also means the Ten Commandments as a Binding Legal Code-Covenant was also done away with as a strict "letter of the law" requirement for Christians.

The ins and outs of Biblical Justification

There is a common claim by Protestants arguing that Justification is strictly a "forensic" matter whereby all the saving actions taking place during Justification occurs entirely external to us. Protestants make this bold claim in order to undermine the Catholic claim that Justification consists primarily in an inward transformation within your soul. A good way for Catholics to refute the Protestant claim is to show how often the Bible speaks of both internal and external language within the same verse. I made a post about this several years ago (HERE), where I cited multiple passages in Scripture which mentioned God performing both external and internal changes on us when we get saved. This dual aspect view is sometimes called the "duplex" view, which even the Council of Trent permitted when it decreed: 

If any one saith, that men are justified, either by the sole imputation of the justice [righteousness] of Christ, or by the sole remission of sins, to the exclusion of the grace and the charity which is poured forth in their hearts by the Holy Ghost, and is inherent in them; or even that the grace, whereby we are justified, is only the favor of God; let him be anathema. 
(Trent, Session 6, Canon 11)

Notice that Trent is not excluding that there is an external component to justification, and it could even be termed "imputation" in some sense (some definitions of "imputation" are okay, while other definitions are problematic). The catch is that the external cannot be seen as the "sole" factor going on, especially to the more central "grace and charity poured into their hearts by the Holy Ghost" (Rom 5:5). Along with the original duplex texts I presented or were in the large comment box (Acts 15:9,11; Acts 26:18; 1 Cor 6:9-11; Eph 2:5-8; Philip 3:9-11; Col 2:11-14; 2 Thess: 2:13; Titus 3:5; 1 Pet 2:24; 1 Jn 1:9), for this post I would like to add a few more duplex verses which I think will be helpful.