Following Jesus in this life is done by faith. We believe and proceed on the basis of God’s word; we act and we live accordingly. A key passage quoted by New Testament writers is in Habakkuk:
but the righteous person will live by his faithfulness—
But they translate or bring that over from faithfulness (though faith is one possible translation of Habakkuk) to faith, perhaps the key passage doctrinally (though Galatians is key doctinally as well) found in Romans:
For I am not ashamed of the gospel, because it is the power of God that brings salvation to everyone who believes: first to the Jew, then to the Gentile. For in the gospel the righteousness of God is revealed—a righteousness that is by faith from first to last, just as it is written: “The righteous will live by faith.”
Key to that is the scriptural narrative concerning Abraham. From the beginning, Abraham by faith responded to God’s call, leaving his country for a place he knew nothing about (Hebrews 11:8). A key point in the narrative (note that it was before he received the command from God to be circumcised, he and the other males with him- Genesis 17) comes later (after Genesis 12):
He took him outside and said, “Look up at the sky and count the stars—if indeed you can count them.” Then he said to him, “So shall your offspring be.”
Abram believed the Lord, and he credited it to him as righteousness.
Later (Genesis 22) Abraham received the ultimate test of faith from God, and according to James his faith was made complete by what he did in obeying, offering his son, the son of God’s promise up to God on an altar as a burnt offering as God commanded him. God stopped him from carrying that out, but we see here that faith is active as well as passive. We stay put and move according to God’s word, his command.
And so the life that is in Jesus is a life that is by faith. And that faith is in response to God’s word, to the gospel/good news in Jesus. We seek to hear God by reading his word which is written for us, or a bit indirectly (sometimes directly) to us. The Spirit helps us by directing our thoughts according to that word, and God’s will for us found in it. So that it is a matter of faith in believing God’s word, in trusting in God, and a matter of obedience, obeying God. Faith is not just a matter of confessing truth, but of acting in response to it, a truth that comes from God to us.
And so by faith I continue on, a faith that is beyond me, but a continued gift from God dependent on him and his grace to us in Jesus. By which I seek to live and follow on day after day. Necessary for each day to the very end.