A believer is someone who follows Jesus.
In a literal sense it means the same as Christian, although that word has become so maligned and distorted that many true Christians prefer to call themselves Christ followers, followers of Jesus, or simply believers.
The usage of the label believer is predominately found in the New Testament book of Acts and various epistles.
To believe is to accept the existence and reality of God through faith, having conviction, confidence, and trust in him; to accept him as real and true.
The word believe occurs hundreds of times in the Bible. Jesus instructed people to believe in him. He said that if we believe in him, we will be saved (Mark 16:16).