Which religion is considered having the most ...

"Observant" is a vague term here. No one can read in all those hearts. In numbers, Christianity is 2.1 billion, muslims between 1.3 and 1.5 billion. These are the biggest religious communities worldwide, and also most widespread. Both are monotheisms of course.

Paul warned that Christianity would become apostate, and in the fourth century C.E. it was flagrantly adulterated through Roman Emperor Constantine. (Acts 20:29, 30) As a result there was a fusion of Christianity with demonistic doctrines that originated in Egypt and Babylon—Trinity, immortal soul, hellfire, purgatory, prayers for the dead, use of rosaries and others. These doctrines are not in the Bible, but they were incorporated into the creeds of so-called Christian churches. They remain there to this day. Moreover, today’s modern churches of Christendom adulterate God’s Word even farther: they have added the higher criticism that tries to undermine the Bible’s authenticity, and the unscientific theory of evolution that denies that God is Creator of heaven and earth and life!
11 Who, then, are the modern-day ‘Philips’ that are safe guides? Those who believe the Bible is the inspired Word of God; who take it as a lamp to their feet and a light to their path; who neither add to it nor take away from it; who let God and his Word be true though they make ‘every man a liar’; and who expend themselves in publicly ‘preaching this good news of the kingdom in all the earth as a witness.’ (2 Tim. 3:16; Ps. 119:105; Deut. 4:2; Rom. 3:4; Matt. 24:14) They use the Bible as their authority, and encourage their hearers to check up on them, not taking their word for it, but taking only God’s Word for it. (Acts 17:11) For you to make a name with God, you should aim to be such a faithful guide, “always ready to make a defense before everyone that demands of you a reason for the hope in you, but doing so together with a mild temper and deep respect.” Or, as Paul said: “Know how you ought to give an answer to each one.”—1 Pet. 3:15; Col. 4:6.
THE PERSONS WE OUGHT TO
BE
12 To make a good name with God it is not enough to study and learn answers. We must apply this knowledge to ourselves first. To benefit personally we must take it personally. Like the man in ancient Israel in the house of mourning, we must ‘lay it to heart.’ (Eccl. 7:2, AV) “Do you, however, the one teaching someone else, not teach yourself? You, the one preaching ‘Do not steal,’ do you steal? You, the one saying ‘Do not commit adultery,’ do you commit adultery?” Even the apostle Paul declared: “I pummel my body and lead it as a slave, that, after I have preached to others, I myself should not become disapproved somehow.” (Rom. 2:21, 22; 1 Cor. 9:27) It is more basic than what we are doing. It is, What are we? What is “the secret person of the heart”? “What sort of persons ought you to be?”—1 Pet. 3:4; 2 Pet. 3:11.

As far as I know, Buddhism is the most observant believers, other than Muslim.  The true Buddhist forbids killing, steal, wanton/licentious/obscene, lies, drink wine/liquor, five so called commandments.

1. Killing -- not only killing human, animals or any living organisms intentionally or unintentionally, it also includes saying things that kill others' confidence, self-esteem, believe, ..., any word/speeches or actions that bring negative effect toward others... etc.

2. Stealing -- taking or possess anything that do not belongs to oneself, whether intentionally or unintentionally, example a pen, that normally will automatically goes into our pocket or bag unintentionally.

3. Wanton/licentious/obscene -- sexually conduct with the wrong person, for example not legally married opposite sex.  Not only non-marriage couples, even legally married couples are not suppose to make love in the day time, at the wrong place for example forest, living room, walkway, bathroom,..etc. The right place and the only place is bed.  In the view of Buddhism, the cause of homosexuality is related to one's constitution as well as from psychological conditions.  From a religious viewpoints, homosexuality cannot escape the item: contradicting morality -- having abnormal sex.  However, from the Buddhist point of view of cause and effect, all worldly sexual desire among men and women, men and men, and women and women contain cause and conditions.  The value of the Buddha's teaching is that the Buddhas and bodhisattvas understand causality very well.

4. Lies -- telling lies, saying thing that is not true.  Other than our daily conversation and salepersons' promotion lines, there are also misleading and fault report in the news media, giving negative effect toward the innocence.

5. Drink wine/liquor -- drinking and get drunk causing inappropriate speeches and actions, for example saying words that hurts other,  quarrel, sexually misconduct...etc.

As a general, Buddhism teaches the existence of passed and next lifes, cause and effect, negative action give negative karma and bring unforturnate consequences to current or future lifes.  These could explain why there are people borned to be unfortunate and some are borned with all the welfare that they could get.  Life is always fair and equal. in Buddhism, there is always an explaination toward any circumstances.

there isnt no answer towards dat sry hunz...

NONE!!!!!!!!!!!!!!!!!!

The more under educated the populace the more vibrant the local belief system.

"Religion" is not mentoned in the word of God. There is only one spiritual pursuit, "Christianity." "They were first called christians in Antioch." Definition Christian; Christ likeness. Religions are man made with man's rituals and designations for self self or egotistical identification. Find yourself a bible believing and teaching church and "study to show yourself approved", "Work out your soul salvation with fear and trembling". Two ordinances of the bible. God is the author of your salvation, not man. Let the word of God be your guide to His salvation.

Christianity