Often when discussing your faith with others, they will question your belief in the Trinity. had Muslims question this in terms of "it doesn't make sense, you worship three gods", and even questioning the historical basis of the Trinity, saying "first you believed Jesus was two-in-one, then later came three-in-one, and even four-in-one, Christians are confused!"
So, what is the basic defense of the Trinity? First you must re-inforce the belief in the Bible (see 2 Peter 1:16-31). Second, you can take it on directly by showing that the Bible teaches that God is one and that each person of the Trinity is the same, and that each is also different. In other words, it may not seem reasonable according to what we've experienced in the material world, but it is clearly taught by Scripture, which is revealed to us by God Himself.
You will need to approach these examples uniquely to how you can most comfortably understand and communicate it. You can point to scriptures such as where Jesus says "I and the Father are One", or John 1 which says in the Beginning was the Word, and the Word was with God, and the Word Was God. (with Jesus being "the Word" and present at creation, in the beginning). You can likewise point to scriptures that indicate they are different. You can use the example from John the Baptist, where he baptizes Jesus in the Jordan, you have a single instance where you have all three present and separate at the same time. Jesus is in the Jordan being baptized, God speaks from heaven ("This is my Son...") and the Spirit comes in the form of a dove.
