For a list of bible verses on the New Testament’s teachings on Non-Violence, check out this write up here (that has helped others).
Non-Violence as Taught in the New Testament is Moral and Good: Christians are to walk by faith and not by sight. For without faith, it is impossible to please God. Trusting in the verses or passages in the Bible on non-violence takes faith. You have to first believe these words in the Bible...
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Important Note: Yes, I am aware that Jesus will return with violence (with his saints following Him into battle; But this is in reference to disembodied saints who have already lived out their faith). In fact, the Christian should expect to avenge all disobedience with their LORD when He returns. So Christians are not Pacifists (in the sense that they are against all forms of violence throughout all points in time). For obviously God told the Israelites to attack various nations, as well.
I think the main issue as to why some Christians think military service would be a sin to them is because it can lead them to disobeying their LORD Jesus Christ in regards to His teaching on non-violence. But we know in the past it was possible for somebody to serve in the military and not act violently. Here is a film that shows the true story of a man who served in battle but he did not take up a weapon to fight or kill anyone.
(Important Warning: This film does contain brief nudity of a man's backside and excessive scenes of violence involving war - and therefore this film is for mature audiences; Also, this Christian is actually SDA. I believe the SDA church is unbiblical because they emphasize the Sabbath and they believe in the additional false teachings and prophecies of Ellen G. White; So while this film correctly upholds the teachings of our LORD on non-violence, it is also a subtle promotion of the SDA church - which is unbiblical).
Today, if one is drafted, they can file for being a conscientious objector if they believe wholeheartedly in Non-Violence.
Again, the issue here would be because of the teachings of our Lord Jesus on non-violence. I don’t know enough about the police department on the issue of non-violence. The internet does not make this information easy to find. So if a police officer changes their beliefs by believing Jesus on the teachings on Non-Violence, how could they still have a job in law enforcement? Could they easily switch to another department that does not require violence? Will it still lead to problems by others? Would it be better if they simply find another job or career? If the police department does require violence or lethal force to be used in all departments, then I would say that a Christian should not serve in law enforcement (because it would be going against the laws of the land and it would be going against what they believe is good and right by our LORD Jesus Christ).
Again, the issue here is about whether or not somebody believes in the teachings of our Lord Jesus Christ on Non-Violence.
So the issue here is about trust. Do you trust the Lord Jesus to protect you (When there are times in your life that God can and will protect you)?
Do you trust that if you are to be persecuted, or tortured for Christ, will you be able to trust in Christ and His strength rather than your own by fighting back? Martial arts is all about trust in yourself and what you can do over what God can do for you.
But what about Aikido? This is a non-violent form of martial arts.
Well, it would be great except that Aikido means ‘the way to union with the universal force.” This impersonal force is known as “chi.” The goal of Aikido is to control both self and environment. Ironically, this martial art is the most compatible with Christianity in regard to its nonviolent nature, but — on the other hand — it is unalterably steeped in Eastern mysticism (or new age spirituality).
Source used for the paragraph on Aikido:
Should a Christian Practice the Martial Arts? | Christian Research Institute
(Note: While I agree with the paragraph I quoted, this does not mean I agree with everything the author says and believes on every topic involving the Bible).
Seeing you believe in ecumenism, I can understand why you don’t see this as a problem. Your way of spiritually is like a broad wide gate path and not a narrow one that Jesus talked about. Jesus said strive to enter the straight gate (Luke 13:24).
Anyways, yoga is tied to Eastern mysticism (false new age practices).
Any discerning Christian will obviously see this as a major spiritual danger and avoid it at all costs (Seeing they are seeking to follow Jesus and not some new age mumbo jumbo). While there is no problem in stretching alone and can be helpful to the body, this is not the case with Yoga (seeing it is attached to false new age practices and false gods).
JW’s (Jehovah’s Witnesses) are notorious in believing this. JW’s are a false cult.
Anyways, I explain their error on refusing blood transfusions in my point #13 in the following thread:
Reasons why the Jehovah’s Witness religion is false (Despite my love for them as human beings and my desire to see them saved). #1. Jehovah’s Witnesses religion came about during the time period of other false religions in the latter half of the 19th century. It is odd that other religions...
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In any event, whether you agree or disagree, may the love of the Lord Jesus Christ shine upon you greatly today.