I found this VERY interesting insight on Facebook today (this is why I keep my Facebook account open, BTW -- it's all about who your friends are):

Why has the verse "I can do all things through Christ who gives me strength." not been applied by Protestants to obeying God's commandments? This is the verse that teaches Catholicism.

Well, you'd never see a "Not perfect, just forgiven" bumper sticker on St. Paul's car if he were alive today. Christ died and rose to give us the strength we need to do God's will...and His disciples do it. They don't make excuses and pretend God has LOWERED the bar of personal holiness and simply offered an amnesty to the world. He has raised the bar and made the strength available for those who are "in Christ" and do receive this strength to live as they ought. There is no forgiveness where there is no change.

The big question is...Where is this strength Paul talks of to be found? In random rushes of adrenaline? In drummed-up emotional fits? Can the strength on which the apostle's ministry depended not have a clear source? If not, then no one can be responsible for being weak. If there is a clear source, then no one has an excuse who does not have that strength.

Some other verses that confound Protestants.

1 Cor 9:27 But I chastise my body, and bring it into subjection: lest perhaps, when I have preached to others, I myself should become a castaway.

Phil 2:12 Wherefore, my dearly beloved, (as you have always obeyed, not as in my presence only, but much more now in my absence,) with fear and trembling work out your salvation.

St.Paul was very far from the heresies of Luther and Calvin like "once saved, always saved" or even worse, "eternal security", "unconditional election" and the like novelties. When pursued to their logical conclusions, these doctrines are fatal to the practice of true Christian discipleship.

Justification is not something merely forensic and external as they vainly imagined, it is interior and transformational. Faith, says the Council of Trent, is the foundation and root of justification, but good works are necessary for salvation after baptism.

God not only actually blots out our transgressions and makes us a new creation, He also wants to destroy the power of sin and concupiscence over our lives, that we the branches may bear much fruit by the power of Him the Vine, which works are truly meritorious as well unto eternal life.

Matthew:  All strength comes from His Precious Blood, which for us is in all the sacraments. Only Catholics have that, no other sect.