“Faith” is the Old English word for “trust”. It is used interchangeably with “believe”. Each of these terms are just another way of saying “to take seriously”. Anyone who takes Jesus seriously (believes Jesus) obeys Jesus because Jesus described serious consequences for obedience and disobedience to His words.
When someone says, “I don’t believe you”, they are saying, ” I don’t take you seriously, I don’t take seriously what you are saying”.
When someone says, “I believe you”, they are saying, “I take you seriously, I take seriously what you are saying”. Anyone who takes Jesus seriously (believes Jesus) obeys Jesus.
For the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God.
(1 Corinthians 1:18, NKJV)
What does it profit, my brethren, if someone says he has faith but does not have works? Can faith save him? 15 If a brother or sister is naked and destitute of daily food, 16 and one of you says to them, “Depart in peace, be warmed and filled,” but you do not give them the things which are needed for the body, what does it profit? 17 Thus also faith by itself, if it does not have works, is dead.
18 But someone will say, “You have faith, and I have works.” Show me your faith without your works, and I will show you my faith by my works. 19 You believe that there is one God. You do well. Even the demons believe—and tremble! 20 But do you want to know, O foolish man, that faith without works is dead? 21 Was not Abraham our father justified by works when he offered Isaac his son on the altar? 22 Do you see that faith was working together with his works, and by works faith was made perfect? 23 And the Scripture was fulfilled which says, “Abraham believed God, and it was accounted to him for righteousness.” And he was called the friend of God. 24 You see then that a man is justified by works, and not by faith only.
25 Likewise, was not Rahab the harlot also justified by works when she received the messengers and sent them out another way?
26 For as the body without the spirit is dead, so faith without works is dead also.
(James 2:14–26, NKJV)