A Christian's conscience should bother them when they lie. If it does not bother one to lie, they have left the faith. Christians are to know the truth. No lie comes from the truth. Christians are to put away lying and to speak the truth.
Christians are to have no enjoyment in lying.
If a Christian does not keep their word, they are lying to God. A Christian's word is to be his bond. A Christian is not to swear an oath. A Christian is not to swear at all. A Christian's word should be good enough, that he would not be expected to take an oath.