God calls all men to be saved. He desires all men to partake in eternal life. He wants all men to be saved and the grace that is offered on the cross is sufficient for all men to be saved. He calls all men because He loves all men so much that He gave His only son so that we may have eternal life. So, God calls and man responds. We answer the call. We respond by loving God back and we love God through obedience to God.
So, in summary, God calls through love (as represented by His crucified Son)—(John 3:16) and man responds through love (represented through our obedience to Christ…”If you love me, you will keep my commandments”).
Standing in front of Christ at judgment, we will be judged on how well we responded to God’s calling. We will be judged on how we loved. We will be judged by how we responded to Christ crucified on a cross.
And all of us will fall short of loving God perfectly because none of us are perfect and all of us at times in our lives have been disobedient to God’s call to love Him and love others as ourselves. So, in Christ’s judgment, we will be dependent on His mercy because we have all fallen short and failed to love Him perfectly.
So, how are faith and works important? We are called to participate in the life of Christ. We are called to unite ourselves to Him in the sacraments. We are called to feed the poor. We are called to clothe the naked. We are called to love God with all of our hearts and to love our neighbors as ourselves.
Out of love, we respond to His call. Out of love—through faith, we do what Christ asks us. These are our works. We don’t do them to be saved. We do them out of love for Christ and depend on His mercy for our salvation. If we don't respond. If we are disobedient to His word. If we don't love. If we don't feed the poor and clothe the naked, then no matter how pious we acted or how much Scripture we read (or how many rosaries we said) He will not know who we are.