Early in scripture when Moses received the ten commandments it is stated that we are not to have other gods before Him,and to not make any graven image or likeness of any thing!Yet we find man doing opposite as he changes the truth of God into a lie to serve the flesh and not the spirit(Romans 1:18-25). 18 For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness;19 Because that which may be known of God is manifest in them; for God hath shewed it unto them.20 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse:21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.22 Professing themselves to be wise, they became fools,23 And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.24 Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves:25 Who changed the truth of God into a lie, and worshipped and served the creature more than the Creator, who is blessed for ever. Amen.

We are known by our fruits which means our life is to be an example we are followers of Christ.Anyone can claim christianity but is there a way to know if someone is genuinely serving Him?Thankfully there is as seen in the following passages(1 John 2:1-6), My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous:2 And he is the propitiation for our sins: and not for ours only, but also for the sins of the whole world.3 And hereby we do know that we know him, if we keep his commandments.4 He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.5 But whoso keepeth his word, in him verily is the love of God perfected: hereby know we that we are in him.6 He that saith he abideth in him ought himself also so to walk, even as he walked.  (John 13:34,35). 34 A new commandment I give unto you, That ye love one another; as I have loved you, that ye also love one another.35 By this shall all men know that ye are my disciples, if ye have love one to another.

For anyone who denies the Lord and are disobedient in serving Him truly show that even if they profess they know Him in reality He is not in their midst!(Titus 1:15,16). 15 Unto the pure all things are pure: but unto them that are defiled and unbelieving is nothing pure; but even their mind and conscience is defiled.16 They profess that they know God; but in works they deny him, being abominable, and disobedient, and unto every good work reprobate.