In Jesus' day, as now, within traditional Judaism there were large numbers of complex and detailed rules for holy living. Someone once asked Jesus what was His simple key to living a Godly life, and, in the proverbial nutshell, He summarised the Ten Commandments in which of the following ways?

A Christian is a person who lives their life according to their belief in God and Jesus. They will accept the Biblical stories of His life, teaching, ministry, sufferings, death and resurrection, as summarised in the Creed/s (a collective prayer or prayers, where gathered Christians publicly affirm such faith). 

As ever, please allow for the fact that various parts of the wider Christian community may be selective as to precisely which elements in the stories they will accept and honour.