1 Tim. 6:20 O Timothy, keep that which is committed to thy trust, avoiding profane [and] vain babblings, and oppositions of science falsely so called:
As an apostle of Jesus Christ, vindicated by Jesus Christ and the Holy Spirit, Paul tells Timothy to keep or guard the things that he has committed to Timothy's trust. Of course, we know that God is the one who calls into the ministry, but Paul entrusted these instructions to Timothy somewhat in the same way that we as teachers and preachers of the word of God entrust them to the younger preachers, praying that they will stay with the stuff and guard the instructions that come from the word of God in order that they may teach them to others (2 Tim. 2:2).
We have spoken a little already concerning vain things. In chapter four, Paul speaks of "old wives' fables," etc. Here he speaks of babblings, or nonsensical words, words which do not bring glory to God and words which are contrary to truth. To avoid these things means to turn aside from them or ignore them as truth, for God's truth is the only real truth. This does not mean that we should not learn as much as we can, but we should always turn aside from those things that are false. This can be determined only from being faithful to the study of God's word.
We should also avoid "oppositions of science falsely so called." The word science here is the Greek word GNOSIS, and it has to do with general knowledge. Sometimes, however, general truth is given for real, firm and eternal truth; thus, it is fasely named, which is the meaning of "falsely so called" from the Greek word PSEUDONOMOS (false name).
Evolution is a great example of this. The study of evolution is an effort at discovering the origin of man, but it is not true; because it is not based upon God's word. The first effort at teaching evolution, in fact, was done in order to destroy the foundational truth of creation by the word of God. The study of evolution has accomplished much of its goal, mainly because many preachers have succumbed to this teaching, leaving the word of God by explaining away the truth of creation. Liberal preachers are a prime example of what Paul did not want Timothy to do.
We must "keep" or guard the truth of creation and many other things that man has tried to destroy, such as salvation by grace, the blood atonement, the precious word of God, and eternal security. Those who have turned from these teachings have not kept the faith. They have turned aside to vain jangling (1 Tim. 1:6) and have turned aside after Satan (1 Tim. 5:15). Let us not do the same.