We cannot serve two masters.
Christ says:
Mark 7:7 - Howbeit in vain do they worship me, teaching for doctrines the commandments of men.
Chirst also says:
Matthew 5:17 - ¶ Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.
Matthew 5:18 - For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.
The Apostle Paul said:
Do we then make void the whole law, and yet offend in one point, he is guilty of all.
For He that said: Do not commit adultery, said also: Do not kill. Now if thou commit no adultery, yet if thou kill, thou art become a transgressor of the law. - James 2:10-11.
James 2:10 For whosoever shall keep the whole law, and yet offend in one point, he is guilty of all.
James 2:11 For he that said, Do not commit adultery, said also, Do not kill. Now if thou commit no adultery, yet if thou kill, thou art become a transgressor of the law.
The Revalator said:
And hereby we do know that we know Him, if we keep His Commandments. He that saith, I know Him, and keepeth not His Commandments, is a liar and the truth is not in him. - 1 John 2:3-4
1 John 2:3 ¶ And hereby we do know that we know him, if we keep his commandments.
1 John 2:4 He that saith, I know him, and keepeth not his commandments, is a liar, and the truth is not in him.