Should Christians avoid secular things (i.e., abstaining from birth control, television, music, movies, etc.) to get closer to God?
The Bible makes clear that our righteousness is not obtained through our personal works. It is imputed to us by our faith in Jesus Christ. As Paul says:
Rom. 4:4 Now to the one who works, his wage is not credited as a favor, but as what is due.
Rom. 4:5 But to the one who does not work, but believes in Him who justifies the ungodly, his faith is credited as righteousness,
Therefore, if we have Christ’s righteousness credited to us by faith, then no work we do can add to our justification. Furthermore, the Bible says the Christian has liberty in many areas of life since we do not have specific restrictions or laws that can ensure our righteousness. Our faith alone in Christ alone assures us of Christ's righteousness.
Obviously, our liberty cannot become license to engage in sin. Instead, the Christian is called to restrain the flesh and walk in the Spirit so as to please the Lord. Asceticism is a practice of self-discipline or avoidance of indulgence to please God through a denial of the flesh. Depending on an individual’s motivation and purpose in this practice, it could be appropriate for a Christian in some forms.
For example, if a Christian is led by the Spirit into a period of fasting, then this form of asceticism would be biblical. On the other hand, if a person practiced abusive treatment of the body to put an end to sin and please God, such a practice would be both wrong and useless as Paul teaches:
Col. 2:20 If you have died with Christ to the elementary principles of the world, why, as if you were living in the world, do you submit yourself to decrees, such as,
Col. 2:21 “Do not handle, do not taste, do not touch!”
Col. 2:22 (which all refer to things destined to perish with use) — in accordance with the commandments and teachings of men?
Col. 2:23 These are matters which have, to be sure, the appearance of wisdom in self-made religion and self-abasement and severe treatment of the body, but are of no value against fleshly indulgence.
As Paul taught, self-abasement and severe treatment of the body is not a means to self-discipline or pleasing God. Instead, we must focus on biblical ways to strengthen the spirit, not waste time trying to degrade the flesh.
Concerning the specific practices you listed (e.g., abstaining from birth control, television, music, movies, etc.), these choices fall into the realm of liberty. Each Christian has liberty to do as he or she feels led in these matters, and no Christian may stand in judgment over another Christian’s choices. As Paul wrote:
Col. 2:16 Therefore no one is to act as your judge in regard to food or drink or in respect to a festival or a new moon or a Sabbath day —
Col. 2:17 things which are a mere shadow of what is to come; but the substance belongs to Christ.
There is no inherently right or wrong way to live in these areas, apart from our requirement to seek for godliness in everything we do as Paul directed:
Phil. 4:8 Finally, brethren, whatever is true, whatever is honorable, whatever is right, whatever is pure, whatever is lovely, whatever is of good repute, if there is any excellence and if anything worthy of praise, dwell on these things.
However, if a Christian is pressured into acting contrary to his or her conscience in matters of liberty, then that Christian will have been made to stumble by excessive liberty, as James taught:
James 4:17 Therefore, to one who knows the right thing to do and does not do it, to him it is sin.
We must take care not to intrude on the personal decisions of others in matters of liberty and thereby to cause them to stumble in their conscience. Leave room for differences without judgment, as Paul commanded: