The word Trinity is not in the Bible

Some critics of the Trinity doctrine claim that since the word "trinity" is not found in the Bible, it isn't true. Furthermore, some assert that if God wanted us to believe in the Trinity He would have stated the doctrine clearly.
First of all, it is illogical to claim that since the word "Trinity" is not found in the Bible that its concept is not taught therein. This kind of objection usually demonstrates a prejudice against the teaching of the Trinity. Instead, the person should look to God's word to see if it is taught or not.
Second, there are many biblical concepts that people believe in that don't have a specific word describing them used in the Bible. For example, the word "bible" is not found in the Bible, but we use it anyway to describe the Bible. Likewise, the words "omniscience," which means "all knowing," "omnipotence," which means "all powerful," and "omnipresence," which means "present everywhere," are words not found in the Bible either, but we use them to describe the attributes of God. We don't have to see a specific word in the Bible in order for the concept it describes to be true.
Following are other words that the Bible does not use but the concepts are mentioned.

Atheism is the teaching that there is no God. "The fool has said in his heart, "There is no God" (Psalm 14:1).

Divinity which means divine quality or godlike character. Yet, we speak of the godlike quality of the Lord God. See Psalm 139.

Incarnation which means the word (God) who became flesh. Yet, this is definitely taught in the Bible (John 1:1,14).

Monotheism is the teaching that there is only one God (Isaiah 43:10; 44:8).

Rapture is the teaching that the Christians who are alive when Jesus returns will be caught up to meet Him in the air (1 Thess. 4:16-18).

So, to say that the Trinity isn't true because the word isn't in the Bible is an invalid argument. Furthermore, to say that if God wanted us to believe in the Trinity He would have clearly taught it in scripture, is also an invalid argument. Something does not have to be clearly formulated in the Bible to be valid. Not all things taught in the Bible are perfectly clear. Take a look at the book of Revelation. It contains many things that are cryptic that must be interpreted after examining all of the Bible. Even then, there are disagreements as to what some things mean. Yet, we know that the truths there are true whether or not we discover them.
Nevertheless, there are scriptures that demonstrate a Trinitarian aspect.

Matt. 28:18, Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit,
2 Cor. 13:14, The grace of the Lord Jesus Christ, and the love of God, and the fellowship of the Holy Spirit, be with you all.
Eph. 4:4-7, There is one body and one Spirit, just as also you were called in one hope of your calling; 5one Lord, one faith, one baptism, 6one God and Father of all who is over all and through all and in all. 7But to each one of us grace was given according to the measure of Christ’s gift.
Jude 20-21, "But you, beloved, building yourselves up on your most holy faith; praying in the Holy Spirit; 21keep yourselves in the love of God, waiting anxiously for the mercy of our Lord Jesus Christ to eternal life."

The Safest Place

And I give unto them eternal life; and they shall never perish, neither shall any man pluck them out of my hand. (John 10:28)

We believe in the eternal security of the saints. First, because they are Christ's, and He will never lose the sheep which He has bought with His blood and received of His Father.

Next, because He gives them eternal life, and if it be eternal, well then, it is eternal, and there can be no end to hell, and heaven, and God. If spiritual life can die out, it is manifestly not eternal life, and that effectually shuts out the possibility of an end.

Observe, further, that the Lord expressly says, "They shall never perish." As long as words have a meaning, this secures believers from perishing. The most obstinate unbelief cannot force this meaning out of this sentence.

Then, to make the matter complete, He declares that His people are in His hand, and He defies all their enemies to pluck them out of it. Surely it is a thing impossible even for the fiend of hell. We must be safe in the grasp of an almighty Savior. Be it ours to dismiss carnal fear as well as carnal confidence and rest peacefully in the hollow of the Redeemer's hand.