“For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek. For in it the righteousness of God is revealed from faith to faith; as it is written, ‘But the righteous man shall live by faith.’” Romans 1:16-17
Who can be saved? “...to everyone who believes...” To the Jew first and also to the Greek = Everyone. Salvation is for everyone from every sin at every place under every circumstance. The power of God delivers those who believe. Salvation operates through faith. What is faith? - Believing.
Do not think for one moment that it is possible to be saved without faith. This raises some definite questions as to the nature of faith and as to the object. Faith is belief, and no matter by which name you call it, it is simply acting upon the word of another. A thousand times a year you act on the word of people whom you have never seen. You follow information which is given to you over the telephone, or which you read in newspapers. You conform to advice given by commentators or columnists. You obey road instructions given to you by strangers. All of these actions are movements of faith.
In the realm of spiritual things, faith is simply acting upon the Word of God. He tells you that you are a sinner. You believe it not only because of what you know to be in your heart and in your own experience, but above all because of the revelation of salvation in the Word of God. He tells you that He came to die for you because He loves you. He tells you that He put your sin on Christ and crucified Him in your place. He tells you that He raised the Lord Jesus Christ from the dead as a sign that by Him all who believe are justified from all things. When you believe that and receive it in your heart, you are saved.
Faith for salvation is trusting and believing that Christ rose from the dead; believing He died for you and trusting Him for eternal life.