These three little words taken from Matthew 28:20 are a huge part of the problem in today's Church. To "observe," in this context, has to do with obedience. While most of us immediately think of the word as telling someone to look closely at, or to study something, we also use "observe" in the sense of obedience when we tell someone to "observe the speed limit." The Greek word is τηρέω (tēreō), means "to attend to carefully." In other words, born-again Christians are supposed to live their lives in obedience to Jesus as their Lord. He is to rule and reign in our hearts.
Most of us appear to be faithful in proclaiming the Gospel (1 Cor:15:1-4), because it is the power of God unto salvation (Rom. 1:16). Most conservative, Bible-believing Pastors and Evangelists present Christ, and Him crucified. At the end of the message, an invitation is usually given to encourage those who have believed for the first time, to "ask Jesus into their hearts." Because all religions teach that a person must do some things and avoid doing other things, in order to earn their salvation, and because genuine Christianity is not a religion but a relationship founded upon grace through faith, preachers are reluctant to tell folks that accepting Christ carries with it the responsibility of living a pure life, and doing good works.
Most conservative, Bible-believing Pastors and Evangelists are very good at encouraging a new believer to be baptized. But due to the fact many denominations teach that baptism is a necessary part of the salvation process (that without it, a person is not saved), baptism is given less emphasis. That is not surprising because while the Apostle Paul strongly stressed that salvation is a gift, that it is by grace and not works, James insisted that unless a person is doing good works, his claim of being saved is a lie (Eph. 2:8-9; Jam. 2:17). Regardless of which position one holds, Jesus wants believers to be baptized.
Where most conservative, Bible-believing Pastors and Evangelists miss the mark is by failing to insist on the new convert being discipled through Christian mentoring and Bible instruction. Christian leaders are to instruct "their sheep" by using the Scripture which is "profitable for doctrine, for reproof, for correction, for instruction in righteousness" (2 Tim. 3:16). If you think preachers are hesitant to insist upon baptism, you should ask them about insisting on discipleship. It is as though they are afraid to exercise the authority they have been given by God to shepherd His flock. It is almost unheard of for a Pastor to tell a believer what he or she has to do in order to grow in Christ, and in His service.
Perhaps the solution is for the message to be as follows: You are a sinner. Your sin requires the payment of death. Jesus offer Himself as that payment on your behalf. If you place your trust in Him, you will be saved. Salvation results in a new relationship with God, Bible instruction, finding a place of service within the Church, and certain persecution by those outside, and often by some inside the Church. Your life will never be the same. Becoming a born-again Christian will take you off the throne of your life, and will result in Christ taking His rightful place as your Lord. We are to "observe all things" He has taught believers to do.