1 John 3:21-22

Beloved, if our heart does not convict us (of guilt), we have confidence (complete assurance and boldness) before God; and we receive from Him whatever we ask because we (carefully and consistently) keep His commandments and do the things that are pleasing in His sight (habitually seeking to follow His plan for us.)

When we believe in something, we are fully convinced that what we believe in holds the truth. Jesus said when we believe in Him, we will receive the promise. Our focus and belief in Jesus open the door for faith to work. When we ask for a need to be met by Jesus, we will receive an answer because we keep the commandments and do what is pleasing in His sight.