For most people, the word "religion" has connotations of "church-going" (or something similar) and "religious activities and holidays." For many, it refers to activities done in an attempt to earn God's favor, or to appease or gain something from him. Many of these things are simply an offense to God; some of them may be acceptable, if one's genuine obligations - which are not religious - are first met. Very little of what is called "religious" is actually commanded by God, but is of human invention.
Everything we need for appeasing God's wrath and for restoring our relationship with him has already been done by Jesus Christ. Adding anything "religious" to his already-accomplished work is an offense and insult to God. For the disciple of Jesus, the only "religion" we can acknowledge as legitimate is the "religion" described in James 1:27. In this passage, we see examples of: 1) love for people (caring for widows and orphans), and 2) love for God (having a life of moral purity). These things are an expression of love that results from what God has already done in our hearts, and do not in any way add to what he has done. [Even under the Old Covenant (Old Testament), when religious activities such as sacrifices were required, people had to trust God, not the rituals, for salvation. Otherwise the religious activities became an offense to God.]
Note the distinction between obedience to God and religious activities (such as Old Testament sacrifices or modern-day "church activities"). God makes such a distinction, so we must also do so. According to God, loving and obeying God, as well as loving (and obeying, as applicable) one's neighbor always takes precedence over religious activities. If a person is unable to do both, he must choose the expression of love (and obedience) and omit the religious activity. This has always been the only legitimate option. (In both Old and New Testaments, God always condemned those who exalted "religion" over love and obedience.)
Does this mean that all "religious" activities and observances are sinful? No, but they have limited value. They are very close to the bottom of our priorities, according to God. Any religious activity, observance or holiday that is not endorsed in the New Testament is not morally binding - and this includes nearly all of them. Though we may be free to practice such things (if we don't neglect our genuine obligations), we have no right to "push" them on others or to condemn people who don't participate in them.
The Place of "Religion"
The world normally defines "religion" in a way that is incompatible with the Bible. Remember that the Bible's concept of "Christianity" (being a disciple or follower of Jesus) is not "religion." (In contrast, fake "Christianity" can accurately be called a "religion," for that is just about all it is.)
A few comments about the distinction between obedience and religion, as an expression of love for God.
When sin is present, and a person is unwilling to deal with it, God hates his religious activities. This is because obedience and religion are not the same thing.
Specific Religious Activities
Though some "religious activities" may be remotely related to "obedience to God," they are not the same thing. Man-made religions tend to distort this fact. (NOTE: This section does not deal with matters such as worship and prayer. When these are genuine expressions of the heart, such activities are better described as "Fellowship with God," than "religious activities.")
Two verse lists are provided as a study help, for those who wish to examine what the Bible says about fasting. [The verse references are placed in one column, with space to the right of them for writing notes.]
Religious Holidays - How are we to respond to them?
Many people celebrate religious holidays, such as Christmas. This is not necessarily wrong, but we must not forget that the celebrating of such holidays is not required by Scripture. They are not commanded. Nor are they forbidden - unless the holidays are given priority over what God does require, or if they have a focus that dishonors or ignores God. This means that those who celebrate religious holidays are not to look down on those who don't, and those who don't are not to condemn those who do (unless those doing it are sinning). [Regretfully, we live in a society that does choose to celebrate religious holidays in ways that dishonor God.]
After all, doesn't he deserve something, if we're going to celebrate Christmas as his birthday? (I realize that there is no way we can know the actual date of Jesus' birth, but most people celebrate it on Christmas.) The answer to this question is "a sacrifice"! This short article mentions 5 verses that use the word "sacrifice" in reference to things we ought to be giving Jesus - a "sacrifice" of praise (Hebrews 13:15), our bodies as a "living sacrifice" (Romans 12:1), etc. Jesus deserves these "sacrifices" - and actually, he deserves them every day of the year!
People may try to suppress the significance of Jesus' birth, but they will never totally succeed. In the end, every knee will bow and every tongue will confess that Jesus Christ is Lord. [Be sure to read the "disclaimer" about some of the extraneous traditions that people have attached to Christmas. I am not defending these!]
I really wasn't sure where to put this. To some, Halloween is religious; to some, it is "neutral" (though I'm not sure there really is such thing as "neutrality" in this matter); and to some, it is totally pagan. I personally have nothing to do with it. But some try to focus on aspects that are not totally incompatible with Christ; or they find themselves in situations in which they cannot avoid it. Currently, I have two articles on this topic. (The link takes you to them.)
"If you love me, you will obey what I command." (John 14:15)
Concerning religious activities (an example from the Old Testament) ...
To obey is better than sacrifice, and to heed is better than the fat of rams. (1 Samuel 15:22b)