The faith-works controversy may be assisted by looking back at the two main covenants of the Old Testament: God’s covenant with Abraham was based on a test of faith; and His covenant with Moses came with moral obligations: the Ten Commandments.

Faith then works; in that sequential order.

In the new and eternal covenant in Christ, a response to God’s invitation in both faith and morality is required. Aided by grace, both are necessary for salvation.

This is why the divine gift of infalibility, bestowed on His Church by Christ, extends to both faith and morals: Freedom from error on the faith and works necessary for salvation is assured by the Holy Spirit through the Church’s Magisterium.